You might want to post this in the Kindle forum. I know that there are a decent number of Canadian Kindle users running around who can answer your questions for you.
The formatting is not a problem. You will have more of a problem with Geo Restrictions then anything. Amazon has a large selection of books that you will be able to purchase. I know that you can download free books from this site, Guttenberg Press, and Feedbooks.
From the posts I have read, the 3G works fine in Canada. Some folks have needed to change the carrier but there is an easy way to do that on the K3 itself. Hopefully someone who has done that will pop on an tell you how.