Husband needs to look at retirement O visa options which you can do aswell if over 50 or look can follow him as a dependant/trailing spouse. Your child could also be a dependant or if of school age possibly an education visa which would mean you could also apply as a gaurdian.
You will need to have your marriage certificate legalised for use in Thailand & translated. We applied for it in Thailand, not sure if that makes any difference
OA only available outside Thailand, you can show the funds in an account from your home country. Alternatively as mentioned you can come on an O or Tourist visa & try to open a Thai bank account very quickly to season your funds.
I think you may be confusing the initial visa & they yearly extension of stay that you will apply for in Thailand at 1900bt a year.
The benefit of the OA is that it can all be done before you leave, the downside is the ongoing Insurance requirement which can get expensive as you age.
There is currently no Insurance requirement with the O visa leaving you free to choose your own level of cover, you will just need to fulfill the Thaipass requirement if it's still going.
I live in Hua Hin & life is pretty much bach to normal. Tourists begining to return & busy at weekends with visitors from Bangkok.
Some bars & restaurants have closed & will probably never reopen so there are changes. Ferry to Pattaya has gone & busses not quite as frequent. Bars generally close when you leave depending on the area but I've been in binta bar until 4am recently, just not so easy to get a taxi home.
You will find that wearing a mask is still required when on the street, in shops & taxis & 99% comply. Pretty obvious that you are a tourist if you don't & expect to get dirty looks from Thai & Farang alike.
If using the trailing spouse route then look up how to get your marriage certificate legalised for use in Thailand. Different methods for different nationalities & might be easier in your home country
Just a heads up, everyone is still required to wear masks, some places will require vacination for entry or possibly a test at entry, so it may be wise to check with any where you plan to visit what their requirements are so save wasted journeys.