possibly but only if you also stick the 800k baht in the bank. If you use an agent to supply the 800k it's only in your bank momentarily so you will likely be refused the 2nd extension due to not meeting the requirements of the first year. This is how you get stuck using agents.
The office the agent uses also comes into play as many immigration offices won't touch you if the stamp is from a known dodgy office.
Good luck with that. Remember that thai embassies take thai holidays so they will likely be closed on the following dates in December, 24, 25, 26, 30, 31 plus January 1 and they quote a 10 day processing time. You'd need to be pretty confident you had all the information required
It depends where you are, if you're in your home country then a driving licence or a utility bill can suffice. If you're elsewhere a hotel receipt and/or a stamp in your passport
Anonymous participant but you won't get a DTV to study. You will need to use an allowed soft power option to follow. You can still study if you want alongside that