One thing to consider trying, which you can't do inside Thailand. It might be possible for you to apply for a Non-O visa as a dependant of your husband once he applies for the non-o visa based on being over 50. If you can get this your age is irrelevant, as is having to place funds in your name in a Thai bank account
not quite true in my experience. After getting a new passport and stamps moved in March I needed copies of both passports for my extension of stay application this month. I also needed both passports when requesting statements from the bank, they issued a new bank book as I'd changed passports. And, although I haven't done it yet, I suspect I'll need both passports when I go to renew my driving licence later in the year.
It's normal that the dates are the same. Usually you can't go earlier but you can always ask, although the reason for the under consideration period is that your application has to go to the head office for approval
exactly this. They don't want to see that one has the ability to borrow 500k for a few days, they want to see that you are able to support yourself inside Thailand which is why they want to look at some months of financial activity at most consulates.
You can't come back to Thailand while waiting for a visa to be issued. In fact you can't leave the country you applied in until it is issued. Thai consulates treat visa applications in exactly the same way as they did when you physically had to hand over your passport and they can check that you have complied with this. There was an example just the other day of someone's application being rejected for exactly this reason.