As I understand it a Thai citizen will get blue book, only foreigner have a yellow, unless your own a condo where its agreed a foreigner can you a blue book. As already started you need to go to the Amphur office, locally.
Find out who offers fibre optic Internet. 3BB always comes out with good reviews and offers 1GPS download at 590thb with limited uploads, price goes up for high uploads
I think the logic is that if your retired you can't work for a company. There is no mention of investment and every retired person with a pension has an investment.
Depends on where you stay, if in Bangkok or the like it would be possible, however, your miss out on a lot of local shops, restaurants and street food.