Why did Moshe choose this moment to ask Hashem to appoint a new leader in his place?
Rashi: Because, now that Hashem instructed him to give Tz'lofchad's portion to his daughters, he thought 1 that perhaps the time had come to claim his own needs, and by the same token, his sons would inherit his position. 2
Rashi: But Hashem replied that it was his faithful servant Yehoshua, who did not move from the tent, who would reap the benefits of his service and take over the mantle of leadership from him - as Shlomo said in Mishlei, 27:18 "The one who takes care of the fig-tree will eat its fruit!" See also Sifsei Chachami.
Why did Moshe use the unusual expression "Elokei ha'Ruchos"?
Rashi: He was saying 'Ribono shel Olam, the mind of every individual ? each one different than the next - is revealed before You! Appoint a leader who will accept each one according to his way of thinking!'
Targum Yonasan: 'The One who rules over the Neshamah of mankind and from Whom the Ru'ach Neshamah' is given to all flesh (mankind)'. 1
This is how Targum Yonasan translates the words. See N'ar Yonasan as to how this answers the question..
