Having written "va'Yomer" in 1:15, why does the Torah repeat it here?
Oznayim la'Torah: This refers (not to Pharaoh's instructions to the midwives, but) to his accosting them. 1
Refer to 1:17:1:1**.
Why was Pharaoh only concerned to kill the baby boys?
Rashi and Targum Yonasan 1 : Because his astrologers informed him that a son was about to be born who would save Yisrael.
Oznayim la'Torah: To solve the dilemma - on the one hand, it would be a shame to kill them and lose their stock of slaves. On the other, Bnei Yisrael were multiplying so rapidly that they were becoming more numerous than themselves, and would pose a threat if they joined their enemies in war. So they hit on a compromise, to kill the boys and allow the girls - who would make fine slaves - to live. And if they would agree to marry Egyptian men, 2 so much the better! 3
Seeing as the idea was to kill the babies before they were born (so that nobody should know that what they had done), how could Shifrah and Pu'ah know in advance whether it was a boy or a girl?
Hadar Zekenim #1, (citing Sotah 11b): Pharaoh gave them a sign - If the baby was facing downwards, it was a boy; if it was facing upwards, it was a girl.
Hadar Zekenim #2: Pharaoh told them that if the mother's thighs become cold, it is a boy, and if they get warm, it is a girl.
QUESTIONS ON RASHI
Rashi writes: "'If it is a boy, [you are to kill it]' - ... As [Pharaoh's] astrologers had told him, that a boy was to be born, who would save them." But the Torah already told us what the Egyptians' motivation was - to stop Bnei Yisrael's rapid increase in numbers!
Gur Aryeh: If Pharaoh's intention was to stunt their growth in population, he should have decreed the opposite - to kill all of the girls. Killing the boys would be ineffective, because any surviving males could marry and procreate with many females. (Rather, Rashi tells us, this decree had a different motivation - to ensure that they would remain slaves forever, by destroying their redeemer.)
Rashi writes: "Va'Chayah - [i.e.] v'Tichyeh (she may live)." What is bothering Rashi?
Gur Aryeh: The word "va'Chayah" appears to be in the masculine (e.g. in Esther 4:11). Rashi therefore expresses it in the feminine.
Rashi writes: "Va'Chayah - [i.e.] v'Tichyeh" (as the word "va'Chayah" appears to be in the masculine; see 1:16:2.1:1). Why, then, does the Pasuk use this term?
Gur Aryeh: According to the Midrash, it could have said 'v'Chayesah,' but one letter is deficient. This conveys the meaning of something missing regarding their remaining alive. Pharaoh decreed, even about the girls, that the midwives not take steps to ensure that the babies would live (as they usually do); but rather that if the baby girl lives, so be it. 1
