Apparently these questions are easily answered.
Marjory LeBreton, government leader in the Senate, says the legal advice they received is that signing a declaration of qualification form that says he is from the island is all it takes. “There is no doubt that senators that sit in the Senate, by way of the declaration of qualification, qualify to sit in the Senate,” LeBreton said.
So, as far as the Senate is concerned, as long as you sign a declaration indicating that you are a resident of somewhere, you are a resident of there. Maybe that’s why the Prime Minister was comfortable declaring that all senators met the constitutional residency requirement.