yes but medical tourist come to Thailand for medical help mostly in a hospital. When recovered they fly back.As far as I remember a visa for medical treatment requires a written statement of a medical specialist
I agree. You can do uit yourself. If you encounter problems you can not solve you can always try a visa office. Not a lawyer! You do not need legal advice!
In general the re entry is near but separated from passport control. Pasportcontrol is just looking at your papers and stamp your paspoort. Re entry is some more work! Photo and paperwork. So i expect near each other but reentry first .