Why does the Torah discuss the Tum'ah of humans after that of the animals?
Rashi: Just as the creation of the animals preceded that of man, so too does the Torah give precedence to the Dinim of the animals.
Why does the Torah insert the words "Ishah Ki Sazri'a"?
Rashi and Ramban #1: To teach us that, even if the baby is born squashed 1 - and resembles a batch of Zera, the woman is nevertheless Tamei Leidah.
Ramban #2 (citing Nidah, 31b): The sequence of the Pasuk teaches us that if the woman 'sows' 2 first, the baby will be a boy; whereas if the man 'sows' first, then it will be a girl.
Seeing as the Torah specifies that a Yoledes is Tamei for seven days, why does it see fit to add "ki'Yemei Nidas D'vosah Titma"?
Rashi: To teach us that she is Tamei Leidah even though she gave birth without seeing blood. 1
The Rashbam learns this from the fact that the Torah does not mention blood with regard to the birth.
What is the meaning of "D'vosah"?
Rashi #1: It is a Lashon of flowing. 1
Rashi #2, Ramban #1, and Rashbam: It is a Lashon of sickness 2 - because when a woman sees blood, she is sick - since her head and her limbs feel heavy.
Ramban #2: It is a Lashon of plague and pain. 3