1) you can stay in Canada for as long as you have a status, as a worker or visitor, etc. Applying for PR doesn't give you status.
2) You cannot stay beyond your current work permit without leaving unless you have applied for another work permit and you're on implied status. It might be worth doing a paper application for a Bridging Open Work Permit whilst waiting for your AOR, I've read posts on here stating that it has worked but you'd need to do more research (or get opinions from senior members on here)