1) I don't know of any Canadian suppliers, but there surely are some. Most of the US suppliers are far enough away from you that it's likely a Canadian supplier would be close enough to have cheaper shipping. Otherwise, Reptile Basics Inc. is generally a name thrown around here a lot that has made plenty of BP.net'ers happy with their products.
2) I'm of the opinion that heat tape under the tub is the best for ball pythons, ESPECIALLY if you live somewhere with indoor temperatures that drop into the 60s in winter. They're pretty good at thermo-regulating themselves, and in a colder areas it's difficult to keep ambient temps up, so it's best to at least have a good hot spot. Make sure you have a hide over the hot spot, and they've have a nice toasty hut to curl in to stay warm.