Travel insurance won’t be accepted a year or two later when you start applying for 1 year extensions. I had an OA for 6 years. I would recommend getting an O visa that does not require insurance
You want to enter Thailand with 6 months or more valid on your passport. Get your passport renewed before entering Thailand. You can check for the procedures on the website for American consulate near you or the US State Department. I renewed my passport with the US embassy in Bangkok. I had to mail my current passport and got my new passport mailed to me 3
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weeks later. Carry both your old and new passports with you. When you enter Thailand go to the BOI office in Bangkok and they will get your LTR visa transferred to your new passport. Your new passport will have a new passport number.
Remember to update your passport information with Thai banks and your Thai phone number.
I don’t know what country you are from but there is probably a similar procedure for other countries.