What are the requirements and process for a 1-Year Extension of a Non-O Retirement Visa in Thailand?

reply to 1, well, it depends

*** if you entered on a 90-days Non-Imm-O Retirement Visa, no proof is needed where the 800,000 THB came from, when you apply for the 1-year extension

*** if you entered on a tourist visa or visa-exempt, and want to apply for the “change” to a 90-days Non-Imm-O Retirement Visa on Immigration inside Thailand, you need a proof that the 800,000 THB came from abroad, and that it sits in the account. No seasoning needed at this point

*** some Immigrations (Jomtien!) ignore this rule, but will want to see a seasoning of 2 months for the application to the initial visa

1 - There is NO requirement that the 800K baht banked money method be transferred in from abroad to get the yearly extension of stay

The only requirement is that the funds be in a thai bank account in your name only for 2 months before you apply for your extension, then the funds stay in that account for 3 months after the extension is granted and after that the balance on the account cannot go below 400K

2 - no, you apply and at most offices the extension is inked into your passport that day (a couple offices Jomtien/Phuket) do require you to come back the following day to pick your passport up with the extension inked in

3 - Not applicable to extensions based on retirement (see previous answer)