Your age is a big factor, and your pre-existing conditions, as they can be related to lots of different complications, resulting in not being covered if you were able to get insurance at your age.
If immigration determines you are trying to stay long term in Thailand they can, and do, ban you from entering Thailand as a tourist until you've been out of Thailand for a considerable amount of time. It is a difference of words used. Some use "ban" when they were actually refused entry until they get the correct long term visa.
It depends on your passport country in whether you can use the income method, as not all embassies issue income affidavits anymore. Because of this bt800,000+ is needed in your personal Thai bank account at least for the full first year. 2 months before, and three months after your first year extension then after those three months the bank balance can never drop below bt400,000+.
the problem with this is age. You can get a retirement visa extension when you are 50, but you can not draw a pension from your home country that early, except in a few situations like VA pensions. So at some point Thailand is going to want to know where the money you live on is coming from, and if tax has been paid on it, as you can not work on a retirement visa extension. That will be targeted first when they start assessing people's tax liabilities.
With a bank2bank SWIFT transfers you can send as much as you want. There is no limit, with any Thai bank. No problem at all SWIFT transferring US$100million if you so choose.
There is no visa requirement to get a driver's license. The only requirement on renewing one is that you are not on a tourist visa in order to get the five year license instead of the two year license. As the DTV visa is a tourist visa you will not get a five year license on renewal, only the two year temporary license again.