No . You have a visa the first year. After that you have an extension of stay based on non OA. And if you want to keep that extension alive you need a reentry for that.
no. If he still has a multiple visa it will just start another year. If he comes back after the visa has expired its 60 days on extemption and he can convert that to a non o retirement. If he has his papers in order. I killed my own non oa that way last year myself. Easy process
Yes. If you getting non o visa. You need passport and a resident permit from immigration. Ask your temporary hotel for the paperwork needed. This is the easiest thing you will ever do in Thailand...
now they know that that option does exist. They can have enough pension too. Not enough information to know if they have that or a good embassy that actually helps...