Best to go to your local IO and get the application form and they will attach a copy of documents required

I am in pathum Thani and when I did my non o extension I asked and was given a reentry form

So yes

I would visit your IO and get a list of documents required as each office has different policies

I was told this by my Lloyd’s bank a few years ago

Get an HMRC account via the app

Barclays are definitely cracking down

The 0 has to season for 2 months before you can apply for the one year extension

USA passport holders get 60 day visa exempt entry which can be extended by 30 days at immigration.Issue with this is that most airlines expect you to have a return ticket within the 60 day period .You qualify for a non o based on retirement which gives you a 90 day entry .Have to apply in USA before travel it’s fairly easy to do online .Major advantage is that you don’t need a return ticket so can come back when you are ready

You are obviously over 50 so get a non o visa based on retirement.This allows you to stay for 90 days .A major advantage is that you don’t need a return ticket so you can go home whenever you want

My comment was that they would realize that you’ve moved abroad