you get a 90 day visa in your home country, and then extend it for 12 months when your in Thailand, no going out the country, however you have to keep 800kthb in your bank for 2 months before the ext and 3 months after, there after you must maintain 400kthb. No insurance needed
It depends on the insurance company, the more risk with a precondition the more they are likely to exclude it, although they normally exclude it for a period of time.