the TM30 can be handled with a simple online reporting system and the 90 day report can just be removed completely. But thai government branches absolutely LOVE their unnecessary paperwork and long queues. So it won't go away anytime soon.
Yes, a new TM30 is needed after every time you come back into Thailand.
Some immigration offices enforce this rule with an iron fist while others don't care at all. But you just need to send a photo of your latest stamp to your agent, so there's no point in skipping it and risking it.
the day thai banking rules start making sense is the day dragons will appear in the sky and start squirting vanilla coke on everyone with green shirts on.
The issue was people who paid agents for f@ke education visas. As in the visa was real but they didn't go to school. It was all bribery and f@ke documentation.