whereas I've seen people in front of me at check in being made to buy either a return flight or a flight out of Thailand before being allowed to check in. As others have said, it depends on the check in person.
safe enough, just need to watch out for pick pockets. Only issue is PP is a bit of a dive. I would look into Da Nang more as someone else pointed out on here.
if you've been up Thailand "for a very long time" then you should know that every change needs to be published in the Royal Gazette before it becomes law.
Some Filipino ladyboys did several months ago and appeared to base themselves down soi 11. The Thai ladyboys fought them at the end of their stay after a bit of build up to the big event and the Filipinos ended up getting escorted out of Thailand if memory serves me right. Not sure what visas they had for their trip but I'm guessing not a non-ED