General of the camp? Im pretty sure a general has power over more than one or a large group of camps
Not really. Depends on the rank of the general in the American Army. There are 4 types of Generals. Each camp is lead by a General.

It's my personal belief that Kefka wasn't truly a general. He was a high ranking government official who earned his office through military action. The process of trying to become a magitek knight is actually what drove him insane. As far as Doma was concerned, I believe that with General Celes being kicked out for being a traitor, that left Leo as the General of the Army. Kefka was like the next in line to be a general. If Leo left, then Kefka, being next in line, would naturally be in charge.