1)
Why does the Torah list the Rosh and the Peder independently?
1.
Yoma, 25b: To teach the Kohanim that they are the first of all the parts to be arranged on the Mizbe'ach.
2)
Why, in Pasuk 8, does the Torah write "ve'Archu" (plural) and here, "ve'Arach" (singular)?
1.
Ramban (in Pasuk 6): Because, in Pasuk 8, the Pasuk is teaching us that many Kohanim gather to offer the Olah, due to "be'Rav Am Hadras Melech", whereas here, the Pasuk is teaching us that it is Kosher even through one Kohen.
2.
Da'as Zekenim and Hadar Zekenim (both in Pasuk 8) and Moshav Zekenim (in Pasuk 9): Because, whereas one Kohen can arrange the limbs of a lamb, at least two Kohanim are required to arrange the limbs of a bull.
