@Morgan ***********
Sadly, for people holding Chinese passports, he will need a tourist visa before entering Thailand, OR get a 15 day Visa on Arrival (which he can not extend). Visa on Arrivals are an "over and done", where there is no other option to extend.
> once we're in Thailand with a tourist visa can he switch to a dependent on my education visa once I have it?
Assuming he does enter with a 60 day tourist visa, it should be possible to get a in-country Non-O visa based on being a trailing spouse off your ED visa - talk to your school first.
Regarding the Green Card, if you have more questions about it, ask at F4USA (F4 is a classification of American visas, but they answer other American visa related questions)
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. That visa advice group would help you further.