I believe you are required to keep the # they give you when you clear(I think it may be for 6 months). They only give it to you when you clear by phone. It usually starts with the year, ie 2007 and has about six numbers after it.
I also always obtain a badge number when talking with them on the phone for anything. It helps so that they dont keep asking you for info everytime you call after submitting your canpass checklist, which i dont believe is required, but helps things go faster.
I have had them ask for different info everytime I called. But if you call and say, "Officer Jones, Badge number 12345 asked me to call back and furnish information about X. Here is the information." It stops the fishing expeditions they have about info.
As for a stamped outbound from Canadia, I have never recieved one and Customs in the US could care less.