RETIRING TO GIBRALTAR

My wife to be (she is a USA National, I am a UK national) are both pensioners in our respective countries and are thinking of moving to Gibraltar to continue our retirement together.

Are there any retirees on here who have made the move?  If so do you have any advice that might be helpful?

Are there financial requirements to allow entry to Gib?  Do you have to be earning so much per year?  I believe we would have to take out health insurance to cover us, is that expensive?
Would we have to apply for visa's and then apply to stay permanently once we were there?

Are there any drawbacks to living on Gibraltar that you have found?

Any information or advice would be appreciated, thanks