> When you land as a PR, all previous visas are cancelled.
This is true. Same happened with my OWP, as I was told the day I got my COPR by the CIC agent at my landing.
As for leaving and re-entering Canada, any valid passport and your PR card is sufficient. Your PR card negates the need for a visa regardless what passport you hold. If you're like me and you have your COPR but not your PR card yet, you may not be able to re-enter Canada regardless if you are holding a passport from a visa-exempt country or one that normally requires one. I have a US passport, but if I flew outside Canada and returned without having the PR card yet, I could be denied entry even though a visa is not required for US citizens (because I would honestly say my residence is inside Canada and am obviously not just a visitor).
I did, however, drive to Watertown, NY and crossed back in with my US passport and COPR and had no problem with re-entry by land, but I wouldn't advise it for holders of passports from other nations, and there is always a risk that a different CBSA agent would decide to take issue, so it's not something I plan to do again until I get my card.