Do you really mean visa on arrival? Or rather Visa exemption? Anyways, if you plan to get an education visa you would have to find a school. They will then provide the documents. With those documents you can go to e.g. Vientiane and get the ED visa there. You will have to extend the visa every 60-90 days. At immigration they might test your Thai skills. So if you don’t plan to go to school, please don’t abuse this visa. Better go and get a Multiple Entry Tourist Visa (gives you up to 9 months of stay with borderbounces every 60-90 days) in your country of residence or a Single Entry Tourist Visa (allows a stay of 60 days with option to extend by 30 more days) and then make a visa run to a nearby embassy / consulate for another one.
How long many months do you wanna stay here?
Oh, and don’t mention anything about working in Thailand, if you don’t have a work permit.
To get an extension of stay you need to bring your passport, a passport picture, a copy of your ID page of your passport + of your visa + entry stamp. You also need to fill in a form (TM7, which you can get at the immigration). The fee is 1900 Baht. It will take some time depending on the queue at the immigration office.
there is no limit on entries (only on visa exempt land entries).
If you have a multiple entry visa you don’t need to take care of anything - just leave and enter again. If it’s a single-entry visa you need to get a re-entry permit before leaving Thailand.
Just go before it expires. They will add the 30 days extension to the original expiry date. So you will not miss out on any days from the extension. Also it's 1900 Baht.
If you go late, you would have to pay an overstay fine of 500B/day.