I'm guessing it depends on whether his wife is Thai or not. My wife couldn't work on her dependent visa and had to get her own extension of stay based on employment, at least that's what her employer told her anyway.
the international schools I visited when looking for somewhere for my kids all wanted to see what visa my kids were on. They were my dependents so no issues but if on visa exempt/overstay then it might be a problem.
she won't be able to work on a visa exempt entry. More likely she'll have to apply for a new non-B outside of Thailand and hope the school pulls their finger out second time round.
speak to the hospital about getting a medical visa then. The IO is unlikely to give two hoots about your treatment when you've been living here on covid extensions.
Sure but be prepared to be quizzed over your covid extensions and not having the correct visa to live in Thailand, which is what immigration will most likely think you're doing.
they don't need to give you a copy when you check in but they are required to file one. Sounds more like they haven't filed one if they're behaving like that. Call their bluff and say you're going down to immigration and you'll give their hotel name and number to the office if asked. Might not have any impact but it might scare them into giving you a copy, assuming they've filed one for you that is.
nothing is stopping you from going before 1 October. Just ask them for a copy of the TM30 as they are required by law to file one within 24 hours of your arrival with them.
sounds more like he's leaving the hotel before going to immigration therefore they don't need to give him a TM30. If he went today, and he was still at the hotel, then they would as the OP has stated.