Have you thought about just buying an accident and critical illness cover policy?? Most other things you could just self insure, where are you staying in Thailand?? I know a good insurance broker in Pattaya I use them myself, and lots of expats use them, it's a British fella that owns it, his Thai staff speak English, you could contact them for a quote, let me know if you want the details.
Slightly different rules for different immigration offices, it gets confusing at times, I personally have dealt quite a number of times with Jomtien immigration, that's what I must have had in mind, thanks for clearing that up anyway.
The new 5 year DTV visa, 5 year Thai privilege visa (very expensive) ED visa, or if you have already fallen in love, the marriage visa, there are other visas, if you have half Thai kids, or you want to start a business.
I used them to open a bank account, and also convert my home country licenses into full Thai licenses, brilliant service, they take you to the transport office and the bank, you don't even queue up, very easy process.
like you say it is better to open an account in the area/province you choose to settle in, because some problems can only be rectified, at the actual bank where you opened the account, with Bangkok bank, out of Provence ATM fees for cash withdrawals (using a Bangkok bank ATM) is ฿15 to use the physical card, or a cardless withdrawal using the application is free!
a lot of people now are saying it's difficult or impossible to open a Thai bank account yourself, on a short-term visa such as a tourist visa, and saying the banks are requesting a long term visa, I think it was some time last year, they tightened up a lot of the rules and regulations regarding bank accounts, you could always try a few banks first, if it's to difficult, an agent in places like Pattaya, can assist you for around ฿4000, yes you will need a Thai account if you plan on staying full time in Thailand, I think the ฿800k needs to be seasoned for two months in a Thai account before you apply.
I have only really had proper personal experience in Pattaya immigration, which is a nightmare, and also a few quiet rural offices, in Pattaya there are only visa agents willing to help for a fee inside the immigration office. and in rural offices, they only accepted completed paperwork to check, wouldn't really help with any decisions regarding most suitable visa, but I've heard of volunteers in other offices, that help out but they always seem busy, he doesn't actually say which visa he wants, but mentions 800k so it must be the retirement visa he is thinking about.
I made a comment to him, saying only use that link I sent for information, about applying on the E-visa website, and said to only use the E-visa official website "directly" and not to go through any third party sites, But yes, good idea you supplying the official link, I'm sure he appreciates the help.