1)
Why are the other sons of Shuselach not listed?
2)
What is the significance of the total number of families listed here?
1.
Rashi (citing R. Moshe ha'Darshan): There are fifty-seven from Yisrael and eight from Levi 1 - sixty-five in all, five short of corresponding seventy nations.
1
Rashi: As the Torah hints when it writes in Devarim, 7:7 "ki Atem ha'Me'at mi'Kol ha'Amim" - ('Hey Me'at') five less than the seventy nations of the world. (whereas "Yatzev Gevulos Amim le'Mispar B'nei Yisrael", in Devarim 32:8, implies that the numbers should be the same. PF). Refer also to 26:13:2:1*, where Rashi explains why. See also Ramban's final comment in Pasuk 58.


