Matt Your present health insurance does not cover you internationally as I understand. If you are planning to live in Thailand permanently . You should consider canceling it. And getting travel insurance during your US visits. And looking into some sort of policy covering you in Thailand.
Paying out of pocket for minor medical issues and return to US for major. That is a chance you take. Because you might have a serious health issue arise where you can’t fly back.
Unfortunately I cannot recommend a specific policy for you.
. You are from the United States? The United States has a tax treaty with Thailand. You only pay taxes to the United States. I lived in Bangkok for three years. I only filed with the United States.
As for how much and what a person is taxed? That depends on the type of income, investments, etc.
The visa service is a lot more than $150. And Siam Legal is not cheap. I suggest you contact some agents and Siam Legal. And get direct quotes from them.