Go to the usps.com website and click on calculate postage and go from there. Insurance is included in USPS Global Express Mail for up to $100 only. Then it is extra for more than that.
I have printed international labels and have found it very easy from their website (using tab that says print shipping label). It guides you through it all, but you still need to stand in line and present it at Post Office (versus dropping it off in those big bins outside the P.O. they now have.) However, I have not yet shipped to Canada, so I am not sure if customs forms are required for them.
Global Express is the only one that lets you track it. It's pretty cool to input the tracking number and learn something arrived 15,000 miles away, and at what time!!