Full payment is required 45 days before the trip; don't rely on AAA agent to tell you.
At that time you can get insurance if necessary.
No idea on a monthly payment schedule; ask the agent I guess.
I was hoping Disney Visa would come out with something so I could save some money. I got to thinking though, I think my airfare is not part of my vacation package. So if I cancelled my package, I would still want AAA to keep my air ressie.