I am not an immigration lawyer, no. If I was, I would be charging for my advice

1) Reply is just based on what people have said on here. More people than not seem to be let in without being reported.
2) If you lose your PR, you would need a work permit if you want to work in Canada. Otherwise you would just be like any tourist who wants to work. You are not allowed to do it unless you get a permit.
3) I have only noticed that people have said they have sponsored their family even though they did not meet the requirements. If you look through the publications on the CIC website (bottom left corner) there are guidelines on residency requirements and when to examine for the residency requirements and that time is basically either as you enter Canada or as you apply for a travel document (outside Canada) or apply to renew your PR card (inside Canada). Even though they ask for your address and employment history for sponsorship, that does not necessarily mean that they are using it to check if you meet the residency requirements. They might just be checking that you were living in the same place where the person you want to sponsor as your spouse was and that you are a hard worker and not sitting around unemployed all the time. Still, it is possible that they check for residency requirements too. No guarantees. Personally I think it is risky to sponsor when you don't meet the requirements. You can discuss this with an immigration lawyer but then you have to pay.