Who will give to the Kohanim?
Radak #1, Malbim: Yechezkel; he is a Kohen. He will give the Korban to the Kohanim to offer it, and he will throw the blood and atone on the Mizbe'ach. In the future, he will be the Kohen Gadol, even though Aharon will be there. Alternatively, he will be second to Aharon. Also this verse teaches about Techiyas ha'Mesim!
Radak #2: According to Chazal, who said that this is the Mizbe'ach that they made in Bayis Sheni 1 , we can say that Yechezkel was among those who returned from Galus Bavel. However, there is a tradition that he was buried in Bavel 2 ! Also the Korbanos that they offered in [Chanukas] Bayis Sheni are unlike it says here, and they built the Mizbe'ach before the Heichal!
Why does it say "ha'Kohanim ha'Leviyim"?
Rashi: Kohanim are from Shevet Levi.
Why does it say "mi'Zera Tzadok"?
Rashi: He was the Kohen Gadol who served in the Mikdash in the days of Shlomo ? therefore they are called on his name.
Refer to 40:46:3:1-2.
What is the significance of a Par Chatas?
Rashi (21): It is like the bull of the Milu'im in the Mishkan. Just like that was burned and not eaten, also this. So Chazal expounded (Menachos 45a) ? they offered Milu'im in the days of Ezra like they offered in the days of Moshe.
