Kevin thats not a visa that is just the thailand digital.arrival card that every visitor has to fill in within 3 days of your arrival to thailand, not linked to any visa
Very simply she needs a uk visitor visa which is a 6 month multi entry visa. There are many requirements she will need to meet and some for you if you are her sponsor. You need to read the uk website to give you an indication of the documents you will need to upload as part of the application along with a visit to the VFS in chiang mai or bangkok availing as.part of the process. It takes up to 3 weeks once all documentation is submitted to gain or not her visa
A bit confused with what your asking? You as a USA individual can enter 60 days visa exempt and then extend in thailand for an addition 30days at a local immigration office, giving you 90 days. Typically you can apply for a DTV with just a single bank statement showing the 500kbaht equivalent in dollars in your own bank ( this is the case with the London embassy) but of course you need to either have a soft power or your own business that allows you to work remotely in thailand to apply, the DTV can only be applied for outside of thailand so in the USA or a neighbouring country but not thailand.
Hi I think you are looking at the non O-A visa which requires police checks and insurance and medical. You i think want a non O over 50 retirement visa where there is no medical, police checks etc. required, only 800baht equivalent in your uk bank. When you arrive in thailand then open a thai account put the 800kbaht in it and apply for a 1 year extension. No insurance or other police checks needed