What is "Ahah"?
Rashi: It is an expression of sighing.
What do we learn from "Nafshi Lo Metuma'ah"?
Rashi citing Chulin 37b: I did not emit semen at night due to thoughts about women during the day.
Radak: My Nefesh is not Tamei from an evil thought, and my body is not Tamei from Tamei food (refer to 1:14:3:2). How do You tell me to eat something Tamei and repulsive?!
Malbim: I was not Metamei my Nefesh via matters or foods that are Metamei it.
What is the Chidush that he never ate Neveilah or Treifah?
Rashi, from Chulin 37b: I did not eat from a dangerously sick animal [that was hurriedly slaughtered before it died. It is like a Neveilah or Tereifah.]
Radak: Kohanim are commanded about Neveilah and Tereifah more than Yisrael, due to Tum'ah - "Neveilah u'Tereifah Lo Yochal Letam'ah Vah" (Vayikra 22:8).
Malbim: I did not eat what is forbidden to Yisrael, nor what is Metamei a Kohen, e.g. Pigul 1 .
What Pigul meat did not enter his mouth?
Rashi citing Chulin 37b #1: I did not eat from an animal that a Chacham needed to rule about (that it is indeed Kosher).
Radak citing Chulin 37b #2: I did not eat from an animal before the gifts to the Kohen (the foreleg, jaws and stomach) were separated.
Malbim: It is proper Pigul (a Korban offered with intent to eat the meat after the permitted time).