You have the Non Immigrant O-A (Long Stay) visa, if you apply for an Extension of Stay you do this with the same reason, being over 50 years of age and willing to sit out the rest of your life in Thailand (also known as retirement).
It is more easy to apply for the conversion to a Non Immigrant O visa based on being over 50 years of age, get a 90 day stay and 60 days later apply for the 1 year Extension of Stay based on over 50 years of age.
If you want to travel during that year, apply then for the Re-Entry permit.
There is no health insurance needed for the visa or the extension of stay. BUT there is an insurance needed for the Thailand pass, which is a different document, now needed to enter Thailand due to covid.
You applied for a 1 year Extension of your current stay, it starts at the last day of your current stay and get extended in two parts. First part is under consideration and Immigration need that time to check if you meet all the requirements, if all done you will get the remaining 11 months of the 1 year you applied for