that is not true. IDP is valid for at least 3 months. Saying that I would always recommend getting a local license. Very easy to do and it becomes a really good method of identification.
I think you will be fine. You should get the letter and that will allow you to extend for 30 days. Then you have those 30 days to put the paperwork together for the 1 year marriage extension. When you get the 30 days extension ask what your immigration office require to extend for 1 year based on marriage. Each office interprets the requirements slightly differently.
a will is something we all should do but most don’t. We did ours recently and it was completely painless. The piece of mind you feel when it is complete is worth it alone.
only difference between Thai and farang is that farang have to pay for the quarantine. All Thais need to quarantine for 14 days just the same. Whether you agree or disagree with the policy of trying to maintain zero cases that is the way it is.
It is always very good practice to have a Thai Will. It is relatively inexpensive to set up. The Thai will will cover all your assets in the kingdom of Thailand. It will make the process of dealing with your affairs so much easier when you do die.
As soon as you get out of quarentine open a bank account and transfer the 400k.
Go to your local immigration office and explain your situation they will either say yes or no to the yearly extension. My thoughts are they will say yes.
If they do say no then towards the end of your 90 day stamp you can apply for a 60 day extension to visit your wife.
At the end of that period (90+60 days) you can apply for the yearly extension based on marriage.