In a year, DTV may not excist any more, so don’t worry about anything until October-November next year.
If want to learn language it is a ED you need, but there are quite strict rules about attendance, since it is based on fulltime study, so there is a risk if you stay away from classes.
Language schools are not eligible for DTV.
As far as I remember, work isn’t allowed on ED.
You can not apply for DTV, when you are on another visa.
You can only apply in your resident country, and absolutely not from Thailand, and remember the oct - march is highseason for visa applications, so the processing time may be longer than the Embassy state on their website.
You don’t get residency rights on DTV, which is a tourist visa, hence you are not eligible for a Thai Bankaccount on DTV.
For residency rights, you need a real to have a real longtime visa, and a workpermit
Search the group for posts, and include the Embassy name in the search, prioritize posts after
****
Most of the questions can be answered by thoroughly reading the website of the Thai Embassy you will apply at, and the manual in the top right corner of the application website, which is a lot more trustworthy source than facebook.