It’s amazing how much easier and less worrisome life can be if you want to stay long term by getting an appropriate long term visa. Trying to get around the system will eventually put you in a precarious situation.
I’ll go out on a limb here and guess that 99% of those working in Thailand remotely, online in other ways such as teaching Chinese students, making a living as digital creators etc are working off the books and in most cases illegally as far as visas and work permits go.
No, you can’t work on the wrong visas including retirement visas.
Nope. Have to have a Bachelors as per Thai law. There are way’s around it but usually aren’t worth the time or the risk. You could try language schools, it seems they have different qualification requirements at times. All of the language schools/private schools/public schools I’ve dealt with require bachelors degrees.