Who were Eldad and Meidad?
Why did they remain in the camp and not go with the other elders to the Ohel Mo'ed?
Rashi and Rashbam (citing Sanhedrin, 17a) and Targum Yonasan: They were originally chosen to become elders, but they remained in the camp, because they considered themselves unworthy of becoming communal leaders. 1
Targum Yonasan: They were running away from leadership (Refer to 11:26:4:1**).
What did they prophecy?
Rashi (on Pasuk 28): They prophesied that Moshe would die and that Yehoshua, would take Yisrael into Eretz Yisrael.
Why were there two elders too many
Rashi: Moshe initially chose seventy-two elders, six from each tribe, even though he required only seventy elders, 1 and he knew that no tribe would willingly forego one candidate.
Rashi: He therefore took seventy-two piece of paper, on seventy of which he wrote 'Zakein', and two of which he left blank, and after placing them in a box, he intended to ask each elder to withdraw one piece of paper ...
And what are the implications of "va'Tanach Aleihem ha'Ru'ach"?