1)
Which Kohanim may not serve on Mizbach Hashem?
1.
Rashi: It is those who offered on Bamos to idolatry.
2)
Why does it say "Ki Im Achlu Matzos"?
1.
Rashi: Regarding this, they did not lose their Kehunah. They may eat Kodshim, like a Ba'al Mum. They receive a portion and eat, but they may not offer (Menachos 109a). "Matzos" refers to Menachos; the same applies to all Kodshim.
