Those canisters don't have compressed air, they have foam that hardens. Good for getting a trashed car tire to a shop to install a replacement, but not good for repairs. Get a tire patch kit (<$10) and you'll be okay. Lots of people carry spare tubes around just because it's faster to install a new tube than to patch the existing tube.

I believe that if you get the right wheel size, the tire will fit, but beware of the clearance between the wheel and the frame. Look at the size of the tires the bike came with and go from there. I ride 700x32 (both in millimeters, so about 27.55"x1.26") and they work great for my commute (14 mile roundtrip).

Don't worry about the details yet. After a few weeks, you'll get some good ideas on what you need and what you don't.