Traveled via Air Canada to YYZ on 9/2 and it only took a minute to get through Canadian customs with my passport. The agent started to hand it back without stamping it, but I asked her to. She said it wasn't necessary, but she would. So apparently an entry stamp is not standard practice.

Returned via YYZ on 9/11 and US Customs preclearance there was also brief--surprising since I was in-transit from YHZ and the plane was late. The baggage did not arrive in time to claim & carry through customs. Air Canada told me to go ahead so as not to miss my onward connection. The agent did look at my passport, but didn't even ask about the lack of baggage from a 10 day trip. (The baggage didn't make my onward flight).

Regarding the correct forms of id, my reading of the immigration information provided with travel literature is "proof of citizenship". Birth certificate, passport or voter registration all satisfy that requirement. I'm sure the agents prefer passport because the other two have no photo and also no magnetic encoding, but they have to accept them. One time when I temporarily misplaced my current passport, I took an expired one on a Canadian trip. The US agent didn't like that either-he couldn't use it in his magnetic strip reader due to the cancellation punches. But it IS proof of citizenship, and since the rules for US citizens returning from Canada don't specify "a valid passport", an expired one also suffices.