egafd.com

On 1. Check out the situation for each country. The UK has different arrangements depending on specific agreements.
You MAY or MAY NOT get an annual increase. If you go to the USA you will, if you go to NZ you won't.
But in NZ you can opt to swap your UK pension for its NZ equivalent and you get the full amount and annual increases. Alternatively, if you choose to retain your UK pension you get it topped up to the NZ equivalent.
Lots to look into.

Mart

UK Gov site

Some health considerations for EU - being out of your country of main residence for more than 3 months puts you in a precarious position without private insurance:

Your only realistic way to live permanently (well, legally) in Aus/NZ/US/Canada is to get a job there before you retire.

You can go to Thailand with only about ?12,000 in a Thai bank, assuming you're 50+