well to be clear, i'm not really on my way on thailand, just close to it. i don't actually have the flight from KUL-KBV yet. but i did fly out of the US jan 2 and am on my way to tunis now. after a week i have a flight to KUL. i can linger in KUL if i need to for doc review and approval, my worry is getting a denial and having to start something over again and from somewhere.
missing from above is what is required to keep PR in Taiwan, although that is a surprisingly minimal amount of being there at least a little bit every 5 years. I'd be concerned about that turning into 183 especially if the government/politicians/people think foreigners are just abusing the program so that Taiwanese citizens pay for their health care.
for the education visa, you needed to attend an accredited school, so if not a university it was an accredited Muay Thai or cooking school. Not sure if accreditation is required for DTV. I've never heard of a dance one, I wouldn't expect that to likely work.
you'll be able to find a gym you like and most should do a pretty good job with new foreigners. I'm not familiar if the DTV requires you to go to the school you attend, but I assume you'll have invested some funds to at least start out as a student at an accredited gym.
You're responsible for the tax, not the company. Tax treaty typically means you owe here if over 180d but home country would reduce the amount you owe by the taxes you paid. You're best off consulting an average accountant
everyone intuits you'd be working there because 99% of the time you would be back home. It's hard enough to start a new business already. You know how to hang up drywall so you do that, oh you can go fix this thing, oh you're the owner so you'll set the schedule, etc. totally fine back home, and here you're arguably taking away from Thai labor for any task you do. So you basically can do none.