Its damn early to be thinking winter, mate!
Anyway, fellow Ontarionian(?) here. I ended up getting Blizzak WS series tire, and some 16" steelies. These tires honestly saved my life on a trip down 401 when the snow was fresh and unplowed. If you're getting new rims though, then feel free to just use your stock wheels with your winter tire.
The window's definitely got stuck ALOT during the winter. Sometimes you'll find that you can't operate them properly anymore (lights flashing on the window switches) when they get stuck. You'll need to force the window to fully closed position to get them working again. It's freezing at the lower edge of the window that you should be worried about, not the top edge by the door seal!
As for rust proofing, I have no experience with the stuff... I would reccomend it for peace of mind. Me personally, I'm gambling that the factory protection is good enough, coupled with a good underbody wash every other week
