Your multiple entry probably expires when your visa or extension expires. That should not be a problem. You confirm with your immigration office that you can apply for an extension of your OA visa by reason of marriage and not be subject to the health insurance requirement.
I would like to confirm the answer to this. I have insurance but that would be plan B.
You will need the Thai insurance if you apply for a 1 year extension when you are inside Thailand. You will need the insurance to apply for a new O-A visa in your home country.
Yes. That is why I did it online this time. Maybe they will change it back after September. In any case I get to go back to CW in October/November for my 1 year extension.
It depends when you last applied. They only started enforcing this after October. When I applied last October none of this including the insurance applied. I will have to meet the new requirements this November.
Note there also another separate letter you need to get from your bank that simply says you have an account. You get this letter no more than a week or a couple of days before you go into the immigration office to apply for your extension.
From what I understand most local branches can only print out 6 months of your statement. To go back a full year then they have to asked the main branch and this is the source of the few days delay. Whatever your bank says. Do that.