Whether all of the placements of oil are requirements: Zevachim 40a, 44a
Whether the placement of the remaining oil on his head is a requirement: Zevachim 6b
At what point is one permitted to use the remaining oil for himself: Zevachim 44a-b
Is pigul intent while bringing the metzora's korban asham significant for the oil, if the oil is not directly rendered permissible by the asham itself: Zevachim 42b-43b, 44a-b
Other
The metzora gains atonement by having the oil placed on his head: Zevachim 6b
Do we consider the blood of the metzora's korban asham a matir for personal use of the oil remnants, since the oil may not be used until the asham's service is complete - or not, since the oil may be brought at a later date: Zevachim 43a, 44a-b