I don't think there is a way to get around that unless you fly up to Canada and get a Canadian credit card.
Yes you can, if you're only picking up a free game (like Godfinger). And yes, there is a "none" option on the credit card dialog.
This is how I created a Canadian account and there was clearly a none option listed. If you tried to edit your current account into a Canadian address (something I first tried) then you won't see a none option.