questions on Sh'lach L'cha

[cellio]

The rabbi pointed out an oddity in this week's portion this morning (for which he did not have an answer off the top of his head): at the beginning of Sh'lach L'cha, when the spies are enumerated, we have "from the tribe of Ephrayim, Yehoshua bin Nun" and then, later, "from the tribe of Yosef from Manashe, Gadi ben Susi". Yosef, one of the twelve sons of Yisrael, doesn't get his own tribe; instead, his sons Ephrayim and Manashe are elevated to full tribal status. So why does the torah give the extra lineage in one of these cases but not the other -- and especially skipping the first instance (where you would expect it were there only one)? The rabbi checked Mikrot Gedolot but didn't find anything there.

And is it significant that Yosef's name is attached not to one of the heroes of the story (Yehoshua), but to one of the defeatist spies who caused the forty-year delay on entering the land?

And on a much more minor note, why is Yehoshua bin Nun instead of ben Nun? (That's consistent, not just in this passage.)