These laws and regulation together with the numerous options are so complex and extended... it's impossible to put a correct answer into one FB post.
Best is to talk to a (decent) realtor and or a lawyer (although you won't need one to buy property you might consider paying one for his advise only) and narrow answers down to your personal situation.
did anything change since last year? Or is it different per province? In Chiang Mai you can get it 90 day prior and within 30 after the expiration date.
Same for Thailand and I guess this rule applies to most nationalities entering the country. Best is that your friend gets a new pasport before traveling. He might get refused boarding by the airline already....