I believe the limit is 60 for state schools and universities but no limit for private schools. I've heard conflicting reports so I guess it's going to be up to the school. There's no age limit for a work permit afaik.
There's no requirement to leave 800,000tb in a bank account once you've received your Non Imm OA visa. You can glean around 2 years from this visa with one border bounce. You will, however need 800k in a Thai bank account seasoned for 2 months in order to obtain a one year extention of stay after your initial 2 years.
Thai cookery courses, many different languages including Chinese and English, you need to find a school/organisation that can assist you with the ED visa because theoretically you dont need a specific visa to study anything in Thailand.
Different scenario. The teacher doing 90 day reports was on an extention of stay not a visa and the one leaving the Country every 90 days was on a multi-entry visa.