it'll be hard to transfer into any world top Universities with AUP ^^
Go through something like A-Level,IB,SAM or CPU if you want to try for high ranking Universities.

Yes, it is possible for an American University Program (AUP) student to transfer to a Canadian University. I'm from INTI college and two of my friends have been accepted into University of Waterloo. INTI college has about 14 partnerships with Canadian U.

Regarding the credit transfers, I'd advise you to check with the Uni. A better way is to come to INTI College and check which subjects are transferable to the U that you're planning to go. There are tons of files in the Center for American Education (CAE) at INTI, just choose the ones that you have in mind and check the subjects accepted.  Alternatively, you can speak with the head of INTI AUP Program (Miss Terrie). Yea, some subjects might not be transferable at all to another university, that's why AUP advisers always advice their students to decide on the U that they want to go by the second or third semester.

Not exactly, but you can do it during your enrollment if you want. Next semester is a short semester, so you'll be taking only 2 common subjects. My first guess is ENL 101 (English) and another common subject which are transferable to all Uni. So do not worry about it first, but it's always good to check early if you have a few U in mind now.