Were the Kohanim in front or in back of the people?
Malbim: The Chalutz (Bnei Gad and Bnei Reuven) went in front of the Kohanim, like it says in verse 9.
What are Yovelim?
Rashi: They are rams.
Why does it say here that they will blow Teki'ah, and in the next verse, Teru'ah?
Malbim: The custom was to blow Teki'ah on days of Simchah, and in war, Teru'ah. "V'Chi Savo'u Milchamah