I do my complete heath Check Up at the Christian Hospital. Recommended by the Swiss Embassy. Easy to get to by bus. Not too expensive. Very professional.
Takes 10 minutes. No Cert needed. Just "double" ID (passeport and diving licence for example). If one branch says no, try another one... shop around in touristic places.
First an Extension of 30 days of your "Exemption Stamp" (1'900 THB), then a 3-months "Non-O" visa (1'900 THB) and then a yearly Extension (1'900 THB). Ask your Immigration bureau which documents exactly you need. They know the best...And don't forget the 800k THB on a Thai Bank account...
So, at least, now you know the answers to all your questions (number of photos, what to copy, how many copies, etc...). You can get prepared with all the requirements. Good luck ! It will work out well if you have all the documents they request. 👍