there are two sides you can go through immigration. Each side has a boot where you can ask for re entry permit BUT sometimes there are still two sides where are the immigration boots but just on one side the re entry boot. If you enter on the side without s re entry boot you go through immigration and via the shoppingcorridor you enter the other immigration from the backside and join the re entry boot. So yes in general first re entry and then immigration but sometimes first immigration walk 200 meters to the other immigration and enter the rentry boot! That is the reason why you get two conflicting answers!
Boi who organise the ltr is amazing. Very helpfull. You write : takes one month. Maybe but that is only possible if you forfill the requirement without hassels. Just reckon two months .
Call AA insure in Pattaya. Dutch very reliable company. They can help you out but many other insurance companies can help you out too. And maybe you can buy insurance in your own country via email