1)
Why does the Torah need to point out that "these three were the sons of Noach"?
1.
Seforno: The Torah is pointing out here that, in spite of the fact that one of the three was the Rasha Cham, 1 HaSh-m blessed them all that they should be fruitful and multiply (9:1). and that the Berachah came true, because they were sons of Noach.
1
Cham had already sinned in the Ark by being intimate with his wife, against HaSh-m's instructions.
