pretty sure the embassy will see he has another visa either deny CoE to find out about existing visa or I guess potentially go ahead and cancel his existing visa and get the immigration office to rubber stamp it as cancelled upon arrival to Thailand.
correct but he said in an older post he entered as a tourist, went onto amnesty and presumably now 60 day covid extension. As such, my comment is correct for the OP.
For expats paying tax I believe they should be subsidised but that's clearly a losing battle.
no, you're expected to attend classes and it's been massively clamped down on so only certain schools qualify for sponsorship. You don't turn up your visa gets cancelled and you'll find yourself on a plane back home.