2

The first set seemed to be the ones who were the taskmasters who took beatings in Egypt in order to protect the people. This site discusses the Rashi which cites the medrash to this effect.


2

One per tribe, as seen in Numbers 1:4, and 1:16. See Also Hizkuni on 1:16 who says this explicitly.


1

Not sure if this counts as an answer, but I'll post two commentators: Rashi (1:16): they were called for all important matters in the camp (administrative duties?) Ibn Ezra: the nation wouldn't do anything until they [the princes] would call them I think this suffices to show that they were in fact leaders of some kind: both symbolic (as they would call ...


Only top voted, non community-wiki answers of a minimum length are eligible