I am in coop right now here in Manitoba, I'm gonna answer all your questions as best I can.
First off, yes you do get paid, generally a half days pay every day but when you work 6 hours or more you get a full days pay, normally you are at "work" for about 5 hours. You take "classes" that are 40 minutes each, sometimes lessons can stretch for hours (stupid military law). You do a lot of drill classes and you're going to go insane everytime you hear "for ease of learning this can be broken down into squads". The other day we had dressing a squad with arms, stripping and cleaning the C7, ethics and morals of the Canadian forces and PT. You get the idea eh? It's basic training.
Yes you do SQ. Assuming you complete the whole course you will be BMQ and SQ qualified. SQ is carried out in the same format as BMQ. You do a 2 week exercise on your SQ, and yeah you go out on weekends sometimes during BMQ for things like firing ranges etc.
During the summer you can go on your MOC training, that is what I am doing, going to Wainright for my Infantry qualification. You don't have to go away during the summer though, and no you don't have to redo BMQ and SQ, those courses are for real.
To answer question four, you will either go for your MOC training or whatever your unit tells you to do.
You join the air force to be a pilot. First get a university degree, you have to be an officer to fly those planes(99% sure). During COOP your trade choices are limited to what is being offered in your are by your units. You can't be a reserve pilot. If I am wrong somebody please correct me.
Anyways just some tips for you if you're going into it. Get into shape NOW. People over here on my COOP course aren't in that great shape, you do lots of running and pushups, sit-ups and ab work. It's important to be fit in the army and important to be fit in life. If you are ever doing PT and you can't go on any longer NEVER QUIT, you can slow down but never stop. COOP is a lot of fun, I hope you do it, it's a great experience and I love it so far.