1)
What if the oil in the Kohen's palm spills before he manages to place iton the Mitaher's head?
1.
Yoma, 61a: It does not prevent the Taharah from taking effect
2)
What is "ve'Chiper alav ha'Kohen" referring to?
1.
Ramban #1: It refers to the blood of the Asham and the oil, as discussed in Pesukim 14-17. 1
2.
Ramban #2 (citing The Sifra): Tana'im argue about what atones - whether it is the remnant of oil that the Kohen places on the head of the Mitaher (R. Akiva), or the Korban Asham (R. Yochanan ben Nuri) 2 .