2) You would get stamped into Thailand for a 60 day stay with a Tourist Visa and you could apply for 30-day extension at immigration for 1,900 baht.
I don't like the word conversion, but with a visa-exempt entry or Tourist Visa you can apply for a Non-O visa in Thailand for 2,000 baht if you meet the underlying requirements for the visa (such as being over 50 - retirement - and meeting the financial requirements). This Non-O visa gets you a 90-day stay which can be extended forever, for a year at a time for 1,900 (you must meet financial requirements). You would never have to leave Thailand again if that were your wish. Trips outside Thailand would require a re-entry permit (1,000 baht) to re-enter Thailand and resume your permission to stay granted on your extension of stay.
How to do this, at least in Phuket is explained at the following two links. First is getting the Non-O in Thailand, second is getting a retirement extension of stay.
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