Medicare, Medicare Advantage, Part D, Oh My

Was anyone on a Medicare Advantage plan before you moved to Portugal? I'm 64 and we are planning on moving to Portugal later this year, but I need to sign up for Medicare now for a few months before we move.  I can either take Medicare A-B & D plus a Medigap, or a Medicare Advantage plan.

What did you do? Were you on a Medicare Advantage before moving? If you ever move back, can you restart it? I believe that Portugal's National Health system counts as having coverage in place, so if we do move back we should not have trouble restarting Medicare Part B & D. 

Do you maintain Part B?

Thanks!