If you have an international driving permit all you need to do is watch a 1 hour dlt driving video and pass a few questions. Take a screenshot of your pass grade, book an appointment and do the reaction tests on the day.
I did mine in Chaam a year and half ago, it was easy and took about 30 minutes for everything including getting the licence.
Why anyone would pay an agent is beyond me (but each to their own) and must be illegal. There are also lots of scammers offering licences, so be careful.
day tourist visa before you come to Thailand. That gives you enough time then to open a bank account deposit 800,000 and apply for the non o retirement visa.
most Amphur refuse to do it, which is why people use Bang Rak. I am usually opposed to using agents, but this is a situation that is well worth it or you will spend as much travelling back and forth to Bkk and getting interpreters, witnesses, documents translated etc.