This is great information for me as well! My wife and I are planning on moving to Canada after our long process to get me immigrated to the United States as our next 5-year plan. Through the course of having her visit me and my family in Canada, she grew to love the country and its culture, food, health care, etc...
I'm in the process right now of getting US citizenship even though the plan is to eventually move. Mostly to make travel and income (job qualification being citizenship) easier.
I do know a thing or two about paying US income tax while in Canada though and it's a bit of a headache you will need to contend with each year.
1. The comment about Canada only taxing Canadian income is not true. They, like the US, tax worldwide income, and unless you file properly you can be subjected to double taxation. Canada has tax treaties with the US and offers tax credits for foreign income to get around this. I just wanted to clear that up in case there was a chance that you might still get residual income from US-based sources.
2. You can't rely on things like tax software or even most tax online services available in Canada as they region-lock it. In other words, it will only present you with options of Province, not State, and dollar amounts in CAD, etc. You do have some options available, but what I'm getting at is that it's not as easy as going down to your local green tax service to get it done, you may need to file the documents yourself or reach out to a specialist in foreign tax filing. It's not difficult to do it yourself by the way, but I realize it can be daunting for some.