I warn in advance that this is VERY wordy. I'm not sure what everyone is familiar with in regards to Edward's personality and such, so I figured too much is better than not enough. This is where I give the necessary credit to the
FMA Wikia for the treasure trove of information contained in their pages.
History
Born to Trisha Elric and Van Hohenheim in Resembool, Edward's first few years were happy; but after the sudden departure of his father during the boy's formative years, Ed was left with his mother and younger brother Alphonse as his only family. The three Elrics lived in peace in the rural village and the boys began displaying a remarkable talent for alchemy at a young age, much to the joyful astonishment of his mother. However, Trisha contracted an illness and died, leaving her two sons orphaned. Even while mourning, Edward vowed to his brother that the two of them would find a way to bring their dear mother back to life by using alchemy.
Edward and Alphonse spent the next few years living on their own in the Elric family home, supported by their close childhood friend Winry Rockbell and her grandmother Pinako, and pursuing the alchemical knowledge necessary for their planned resurrection. Although they had gained a great deal of information and comprehension regarding the extended basics of the craft, before long it became apparent to the young prodigies that there was only so far they could go while being self-taught. In a stroke of good fortune, Resembool was visited by an exceptionally skilled alchemist named Izumi Curtis who, after some persuasion, agreed to take the Elric brothers on as her apprentices provided they pass a preliminary test. She brought the boys to Yock Island near the town of Dublith in the southern region, where she informed them that they were to survive for one full month without alchemy. If, at the end of their ordeal, they could correctly explain the concept "One is All and All is One", they would begin their training under her wing.
While there, the brothers discovered self-reliance and gained new abilities and insights relevant to living in the world under their own power from having to forage and hunt for food as well as fend off periodic attacks from Mason, an employee at the Curtises' butcher shop who had disguised himself as a masked wild man at Izumi's behest. Coming to realize that, as a human, he is but a small part of the world and universe as a whole, but that the world and universe cannot exist without a collective of small parts, it is Edward who answered Izumi's riddle properly when she finally returned. For the next five months, the Elric brothers were subjected to Izumi's intensive alchemy and martial arts training, growing significantly in both mind and body and gaining a great deal of alchemical knowledge before returning to Resembool. Though instructed specifically by Izumi to understand that death is an irreversible part of the flow of the world and that acceptance of such is important to the "One is All, All is One" concept, the boys dove headlong into their plan to resurrect their mother upon their homecoming, having advanced their knowledge while abroad and discovered the basics to a forbidden practice called Human Transmutation.
Devising a Human Transmutation Circle, amassing the elemental ingredients for an adult human body and offering their own blood as soul and biological data, the boys initiated the Human Transmutation secretly in their home. Unfortunately, the Human Transmutation resulted in a Rebound; Alphonse and Edward were pulled into The Gate. Encountering the mysterious being called Truth, Edward was stripped of his left leg in exchange for crossing into God's domain and peeking at the Gate's vast wealth of alchemical knowledge. Maimed and bleeding, Edward was returned to the human dimension to find that Alphonse had not yet returned from his disappearance into the Gate, that the mother they had attempted to revive was a grotesque mass of organs only capable of sustaining life for a few moments and that his own sojourn into the Gate had granted him the curious ability to perform transmutations merely by clapping his hands together, without the aid of a Transmutation Circle - in the same style used by Izumi. Desperate to at least have his brother by his side, Edward willfully performed another Human Transmutation to call him back, this time sacrificing his right arm in exchange for Al's soul, which he bound alchemically to an antique suit of armor with a Blood Rune before passing out from severe blood loss. Alphonse carried Ed to the Rockbell house, where a shocked Pinako and Winry performed emergency surgery to save the young boy's life.
For some time afterward, Edward remained in a sorrowful torpor until Lt. Colonel Roy Mustang arrived in Resembool upon seeing of the letters the boys sent out to find their father (when their mother had died). Upon discovering the bloody remains of the brothers' failed experiment, Mustang confronted Edward at the Rockbell home and persuaded him to consider joining the State Alchemist program as a means to perhaps restore his limbs and his brother's body someday. Edward, driven by the guilt of what his ambition had done to his little brother, commissioned Pinako and Winry to craft him an automail arm and leg in order for him to follow Mustang's advice. When told that the surgery would be excruciating and that recovery would take at least three years, Ed commented that the pain would be nothing compared to Alphonse's suffering and promised to finish recovery in a single year.
In the fall, his new automail limbs complete, twelve-year-old Edward ventured with Mustang to Central City to apply for his state certification. After passing the written examination and psychological evaluation, Edward astounded all the officials present - including the Führer, King Bradley himself - with his superb and unique abilities and even managed to win the Führer's favor with his brazenness. Within a week, he was issued his license and the symbolic title of "Fullmetal Alchemist". On October 3rd, Edward returned to Resembool, packed up his belongings, burned down the Elric house (claiming that, without it, he and his brother would have no means of turning back from their goal) and left home with Alphonse to find a way to restore him to normal.
Personality
On the surface, Edward displays an immature sort of personality. He is decidedly stubborn and strong-willed, frequently letting his pettiness and vindictiveness get the better of him (it is this stubbornness that contributes to Führer Bradley's decision to codename him "Fullmetal", as "Hagane" is a term in Japanese that denotes someone of obstinate disposition); he is somewhat selfish and remarkably self-absorbed, generally acting more out of self-interest than any sort of philanthropy as well as taking several opportunities to stroke his own ego or flaunt the governmental power and monetary license of his military position. He is largely hostile towards figures of authority and feels little incentive to follow orders with which he disagrees, earning him the distinction of being a loose cannon of sorts, and is also rather quick-tempered, resorting more often to steel-fisted violence rather than calm negotiation to settle disputes (even going so far as to suggest that refraining from hitting Paninya because of her gender is a sexist notion and, therefore, against his principles). He has a reputation for being foul-mouthed and is an incurably sarcastic cynic, only too happy to bluntly and harshly relieve others of their comfortable delusions regarding god, fantasy, or their own self-importance. Edward has also displayed a propensity towards impatience and an inability to sit still for long, which perhaps contributes to his love of travel.
However, for those few people who have made an impact on him, Ed shows his deeper nature to be one of marked selflessness, unflinching loyalty and great compassion. As someone who has had to suffer greatly at such a young age, Edward cannot ignore the true suffering of others and becomes sympathetic upon sensing pain and resolve in people's hearts. Though his solemn advice to such people is often tempered with brusque criticism, it is only because he genuinely wishes to place them on the most direct path forward. As one who had to struggle with a maimed body, he urges those with healthy bodies to use their strong legs to move forward and as one burdened by the mistakes of his past, he stresses the necessity of people taking responsibility for their own errs. Though he will intervene on behalf of the oppressed if he concludes that a situation has called for it, Ed tends to help only those with the will - but not the means - to help themselves, in which case his recklessness and disdain for authority often has him bending the rules to dole out a Robin Hood-esque justice in accordance with his strong belief in the concept of Equivalent Exchange, earning him notoriety and popularity as a "hero of the people".
Of course, the most noticeable of Edward's dispositional characteristics is his Napoleonic denial of his shortness. Even in moments of relative composure, any and all references to his stature cause him to violently lose control of his emotions and lash out both verbally and physically. Distinctive to these outbursts is Ed's tendency to take even the most casual mention of his height as a gross insult and interpret it exaggeratedly, mistaking words as simple as "small" for phrases as contrived as "so-tiny-that-he-need-not-fear-being-crushed-by-a-boot-because-he-fits-so-easily-between-the-grooves-of-the-sole" and the like. Those unfortunate to utter the word "small" in his presence are fated to suffer one of his vindictive tantrums. Though Edward proudly professes that he does not believe in gods, his spiritual sensibilities tend more toward the agnostic than the atheistic; in private, though he does not pray, he frequently acknowledges the existence of a god in his speech, if only to justify why it is that his life has been so difficult.
Ed's aesthetic sensibilities are also quite twisted in that he is a great fan of gothic or macabre fixtures and will usually transmute decorations filled with monstrous or demonic imagery and unnecessarily gaudy details, much to the dismay of anyone who receives a gift or service from him. He has also made it known that his trademark red cloak is part of this general lack of taste, as it is "a badass man color [that] gets the blood going".
Abilities
Despite Edward's small stature and young age, he is a remarkable combatant. Having apprenticed under Izumi Curtis, Ed was taught to condition his body through regular workouts and sparring as part of her philosophy, "to train the spirit, first train the body." As such, his slight frame belies a compactly muscular build that, in addition to his naturally high energy level and endurance, fuels his considerable strength and agility. Due to Izumi's spartan training, Ed has become a particularly competent hand-to-hand fighter, able to hold his own against armed opponents and even skilled martial arts practitioners. Besides that, his steel right arm and left leg augment his fighting strength by adding to his defensive and offensive capabilities as well as his speed - he can even transmute his arm into a blade.
As suggested by his unprecedented acceptance into the State Alchemist program at such a remarkably young age, Edward Elric is an alchemical prodigy of genius level intellect. From early childhood, he displayed a proficiency for alchemy, acquiring self-taught alchemy skills and comprehension from the advanced literature in his father's abandoned study at an age that shocked even his mother. Having incorporated alchemy into his life during his developmental stages, Edward sees the world alchemically and is therefore able to solve complicated codes, puzzles and mysteries much more easily than normal. He also showed himself to be exceptionally adept at chemistry and reasonably competent with biology; indeed even his preparations for the failed attempt to resurrect his mother were indicative of these. Ed's near-encyclopedic knowledge of alchemical theory is astounding and contributed to his incredible success with emergency Soul Binding experimentation. He shows an uncanny level of focus that allows him to effectively shut out everything from his surroundings and devote all of his considerable mental power to whatever problem demands his attention, especially in the case of books.
On The Failboat
As the events circulating around Hughes's death start taking effect, Edward, Alphonse, and Winry are on the train to make a trip to Rush Valley. Edward falls asleep, pressed against the familiar feeling of cool steel on his cheek and shoulder. Nothing out of the usual, nothing that would hint that his life was about to make a very unusual turn.
He wakes up on the floorboards of the MS Elegante - alone, confused, and desperately trying to find his brother and Winry again.
And here is the almighty
Ms Elegante App for future reference