1)
Why does the Torah write "ve'Shachat osah" and not 'u'Shechatah'?
1.
Sifra: To preclude an animal that one exchanged for the original Korban and its baby from the Din of Tzafon. 1
2)
Why does the Torah add the word "le'Chatas"?
1.
Rashi: To teach us that, when Shechting a Chatas, one should have in mind that one is shechting it for the sake of a Chatas.