You might have liked Koh Samui from the pictures. I have been there 4 times, first 2003. when they opened their first siupermarket, a mini Lotus Tesco. Everything there is at leat 30% more expensive than in the mainland Thai.
Unless you are a millionaire who can afford to live near the beach, you may end up in the sticks, with interrupted water and electricity supply. You would not even know there is the sea nearby. Try to rent there, see the prices.
Over touristed. My daughter (a Thai national, then 19 years old) asked me: "Why the hell did we come to this shithole"?
No difference in price? No difference. The agency somehow puts that money into your account (that they open for you).
After the initial retirement "O" visa, the prices as above, 22,000 Baht a year for them to handle it, extend it for another year, including 90 days reports.
No bank would ask you about your marriage status. If you have a Thai partner, official or not, he/she would be a mere translator. Bank staff speak enough English to that extent anyway.
O-visa (can be 90 days),EVisa, plus "yellow book" would let you open a bank account. While doing that from within Thailand, no health insurance (from overseas), no police check report from your country of residence.
That is what I am intending to do: get "yellow book" on the condo I own in Bangkok, O visa 90 days, open a bank account, transfer 800,000 THB, let the funds sit in there for 2 months and apply for a retirement visa.
Impossible. How could the Philipinos even come close to teach maths or anything other than English in Thai? Thais can not teach maths , science or anything?