Why does the Torah write that Shem too, had children?
Ramban: Because it delayed mentioning him until after his younger brother Cham, 1 leading us to believe that he had no children, the Torah comes to refute this
Why does the Torah write that Shem was "the father of all of the sons of Eiver (his great-grandson)," seeing as he was the father of all of his descendents?
Rashi and Ramban: "Eiver" is referring, not to an individual person, but to all the inhabitants of the other side (of the Euphrates River). 1
Seforno: It does indeed refer to Eiver, and what the Torah is telling us here is that there was born to Shem an offspring who resembled him in righteousness, and whom Shem therefore taught 2 to go in the ways of HaSh-m. 3
Since we find that a teacher is sometimes referred to as a father, and a disciple as a son (See Seforno).
Who was the oldest of Noach's sons, Shem or Yefes?
Rashi: Yefes must have been the oldest, 1 since Shem reached the age of 100 only two years after the Flood, whereas Noach's eldest son was 100 when the Flood began. 2
The Ramban agrees that Yefes was the oldest, and he only may argue with Rashi as to who was older, Cham or Shem; refer to 10:21:3.3.
See Sifsei Chachamim.
In what order, and in what year of Noach's life, were each of his three sons born?
Mizrachi: Cham 500, Yefes 501, Shem 502.
Gur Aryeh: Yefes 500, Shem 502, Cham 503 or later. 1
Why does the Torah refer to Shem as the brother of "Yefes the great," as if to exclude Cham?
Rashi, Ramban and Targum Yonasan: Because Shem was in the same league as Yefes, whereas Cham was not. 1
Targum Yonasan adds that Shem and Yefes were brothers in Yir'as HaSh-m (See Peirush Yonasan). The verse also means to emphasize that it is not because Cham was greater than Yefes that the Torah mentions Yefes after Cham.
QUESTIONS ON RASHI
Rashi writes: "The father of all 'Bnei Eiver' - the inhabitants of the other side of the River, was Shem." Why not explain that he was the ancestor of the person named "Eiver" (as Seforno in fact explains)?
Gur Aryeh: Why would Eiver be singled out among all of Shem's descendants? Rather, it means "the other side [of the River]." 1
Gur Aryeh adds: Rashi concludes with the words, "was Shem," to clarify that we are talking about Shem himself, and not about an unspecified son of Shem.
Rashi writes: "... Noach's eldest son was 100 [at the time of the Flood]." How do we know that Noach began to have children at 500; perhaps that is when his three sons finished to be born (and the youngest was 100)?
Mizrachi #1: The reason that Noach was not granted children until 500, was so that his children would not be subject to their own Divine judgment (at age 100) at the time of the Flood (Rashi to 5:32). If all three sons were born by Noach's year 500, they would in fact be subject to Divine judgment. 1
Mizrachi #2, Gur Aryeh: Furthermore, Shem turned 100 only two years after the Flood (11:10).
Rashi writes: "'Achi Yefes ha'Gadol' - ...this means that Yefes was the eldest." But it is also possible that Cham was the eldest and born when Noach was 500, Shem at 502, and Yefes at 503 (in which case, "ha'Gadol" would mean "older," and would refer to Shem).
Mizrachi: Because the verses do not specify exact years, we must assume that the sons were born in three consecutive years. 1 Yefes must have been the one born in 501 [and he was older than Shem, but not the eldest son].
Gur Aryeh: If so, the verse should have written, "ha'Gadol Mi'menu (older than he)." Since our verse means that either Shem or Yefes was the eldest, and Shem was born when Noach was 502, Yefes must have been the eldest. 2
