just had a thought, for my visa extension I live with my wife, and have fill a Thai form also residence certificate, it requires the house owner. Details. And copy of the blue book and her ID
BTW I got a second sim on AIS, account, it was in my name and they needed my passport, I called them about my first aacount and asked them them is the second there and verified, its there but not verified, you need to go into AIS with your passport to do that, it might be worth a call when your back make sure its verified. The helpline is good
The "normal" thing here is that your name match on your AIS and Bankok bank are different or the AIS account has not been verified. Just take your documents into your branch and they should release it. By the way do you go into your local bank regularly?
I can't offer tax advice, but I saw recently that YouTubers in Thailand have been told they should pay tax, in their case they are making content of Thailand. If your work is totally un-connected to Thailand its different. But dont forget money remitted to you from outside Thailand is very like taxable.
I think its 15, but a parent can open an account on behalf of a child under that age, but the parent is responsible. I'm not sure if the child can use all the facilities, like debit card, probably not.
outside of Bangkok private school will be cheaper, I pay 60kthb school fees a year. Its a Thai private school, but a young person should pick the language quickly.