2. If you're happy with the rest of the components of the bike, it's probably simpler to get the complete bike, and then just swap the rear wheels. If you are going to change a bunch of other stuff too, get the framset and build it up yourself.
3. You'd need to get some straps. That said, the only time I've removed the front wheel was to fix a flat. Do you see yourself having to remove the wheel often?