Why does the Chatas always precede the Olah?
Rashi: It can be compared to an advocate who appears before the king to intercede on behalf of his client; after he leaves the presence of the king, a gift follows. Here too, the Chatas is the advocate, and the Olah, the gift.
Moshav Zekenim: This is to show that Ba'alei Teshuvah are dear to Hashem.
What are the implications of "v'Lo Yavdil"?
Rashi and Rashbam: This means that the Kohen cuts only one of the two Simanim of the bird. 1
Targum Yonasan: It means that he should not sever the head from the body completely.
What is the definition of "Mul Oref"?
Rashi: "Oref" is the back of the head that begins to slope towards the neck; "Mul Oref", the continuation of the slope incorporating the entire (back of) the neck.