If you in Bangkok, go to embassy of your country and ask for certificate of residence (address of your condominium or hotel) after that go to open Bank account. Bangkok Bank it’s most easy.
the ocean there’s it’s not beautiful same Andaman ocean but you can swim you just beautiful with jellyfish when there’s has raining. It’s not all season
Hua Hin it’s good choice not cheap for living but not crazy expensive as Phuket. Another choice is Phang nga it’s cheap for living even if you need medical or big supermarket you can drive to Phuket just 1 hour.