Who was Chovav?
Ramban: It is normal for someone who converts to change his name. The Rashbam too, equates Chovav with Yisro.
What was Moshe referring to when he told Yisro "Ki Hashem Diber Tov al Yisrael"?
Ramban: He promised him a portion in the spoil that they would capture from the Kena'anim - silver, gold, clothes, sheep and cattle. At least, that is what Yisro understood.
Targum Yonasan: He was referring to the good that Hashem promised He would bestow upon Geirim. 1
See Na'ar Yonasan.
Rashi writes that Moshe included himself ("we are traveling
Refer to Shemos 4:13:151:1-3.
Rashi writes that they delayed in the Midbar 40 years due to the sin of the complainers. The Mechilta (Pesichah to Beshalach) says that Hashem delayed them so they could learn Torah when their food and water is supplied, or so the Kena'anim can fix what they ruined, and Yisrael will inherit a land filled with good!
Riva (Shemos 16:35): Rashi does not mean that the 40 years were decreed due to the complainers. Rather, through the sin of the complainers, it transpired that they did not enter Eretz Yisrael.