Information in Canadian Immigration Sysytem

Hello Everyone,
Just wondering if anyone have idea about what information are normally inserted into the Canadian immigration system when we come to Canada with temporary resident status, such as study permit, work permit, visitor visa, etc.

Do they insert each and every information that we provide in the main application forms? I heard from some one that they only insert some important comments from the application file nothing else. is it true?

Just wondering , do they insert previous employment history, travel history, etc.

I am asking this , as I am working in Canada over the last 2.5 years and planning to apply for CEC soon. I did not keep a copy of my initial work permit application and I was wondering if any information in my PR application mismatch with my initial work permit application , is it going to be a big problem.

Thanks,