driving in Canada/speed tickets
Good news is, if you're from the States and get a ticket in Canada, it doesn't follow you back - just pay it and it's done with.
As far as using US dollars, you'll get a better exchange rate if you charge everything. Most cards don't charge a foreign currency fee, but some do.
Guillermo,
I travel to Ontario a couple times a year at least, and have taken a few motorcycle trips across Canada. Most places don't seem to mind taking US dollars - and many of them will even give a decent exchange rate. On this last trip some kid working at a Tim Horton's took US dollars on par - but with the dollar so low it doesn't matter too much on small purchases.
trs,
driving in Canada is pretty much like driving in the US - except that generally people in Canada are more polite for the most part. Gas is more expensive there, of course - more of a real world price.