I don’t know the requirements to get the original 90 day visa but after 90 days you would apply for a 1 year extension. When you have an O visa you do not need insurance to extend that O visa for 1 year. In order to extend an OA visa for 1 year you would need to have 1 year of health insurance.
You mean the US embassy in Bangkok. I did this in April. Everything done by mail. It took 30 days for me. They changed the process for paying for the return envelope. Good luck with that.
The branch I have an account with is on Sukhumvit next to W District. I hear that the branch in EmQuartier, Phrom Phong, is easy for expats to work with.
LTR - Long Term Resident visa offered by the Thailand Board of Investment. There are several categories of the visa. I have the pensioner LTR which requires a passive income of $80,000/yr and health insurance. 50,000 fee baht for 10 years. Google LTR Thailand BOI for the website
I believe the 50,000 baht limit has something to do with Wise transfers. If you do a traditional wire transfer you can wire just about any amount. I wired transferred over a million baht to Kasikorn in order buy a car last year and similar amounts while building a house.
If your goal is to never put money into a Thai bank then you will have to return to your home country every 1-2 years to apply for a new OA visa. This plan works for some people.
Another thing to note is that the OA visa requires health insurance both to get the visa and to extend the visa. The non-O does not require insurance for one year extensions. I had an OA for 6 years and now I would recommend the O visa. I got a 10 year LTR in January and I would recommend looking into that as well.