Thanks everybody for your input. Black and white was all I needed.
Couple of pieces of advice: make sure to ask to have a re-entry stamp in your passport. One time is only ฿1000 but multiple reentry will set you back about ฿2500.
Also, in the instructions it said: have a picture of you in front of your building with the number of the building visible or a picture of you in front of your apartment with the number visible. When I saw “or” I assumed that just the apartment number would be good enough, but I have to bring a picture with the building number after all. 
I had a hard time opening a bank account in Phuket. I went to several banks, but they gave me the same excuse that they need a retirement visa to open an account for me. I told them that I can’t get a retirement visa unless I have 800,000 in the bank, so it’s a vicious circle. Can’t open the bank account without the retirement visa can’t have a retirement visa without 800,000 in the bank account. Any Suggestions?