Thank you

On a tourist visa in Phuket. All they asked was tm 30. But, now, I'm in Bkk

There are 2 imigration offices in Bkk, I used one for extension, the other one for tm 30. I'm not sure which one I should visit.

Yes you can. Most of the people don't have a license. You'll have to pay a small fine if you ride a bike and probably no fine if you drive a car. You can also get a Thai driving license. It is the easiest license to get in the entire world.

In Bkk

For me, when I needed a stamp the lady said no problem after I fix my tm30. After a few hours, I came and the male officer told me to file the 90 days report at the same imigration. So, it is up to the officer.

I would not get that kind of visa with a Muay Thai gym. You might have to pay the full amount for Muay Thai training for a year which is going to be overpriced since they count two sessions a day. Then, if you pay ahead, I am pretty sure the trainers are not gonna care about you. Plus, nobody know what is going to happen during the year. The gyms can get closed again and nobody will return you the money. It's better to get this kind of visa from some self defense school and chose a gym you like and pay by month if you really care about good Muay Thai.

Or, maybe a miracle happens, and they come up with a new visa instead of the STR and METV) I just don't want to get kicked out after 3 months