No, you can't work as a pilot with a resident permit, only as a citizen.
No, you can't fly commercially on your JAA/FAA licences.
N registrations here in Brazil? Not in commercial service there aren't. I don't have the time to look it up (possibly in RBHA045 or RBHA047) but all commercial flights are done on Brazilian registered aircraft with Brazilian citizens at the controls.
TTFN