Are you in Thailand already? You can make it until January if you use land border bounce agencies, but depending on where you are it could be some long drives because of the Cambodia border closures. You also have the option of using safe entry services at the airport if you wanted to fly out and back in, but could be a bit more expensive than land border bounces. More comfortable though.
Definitely. But why wait? Get the DTV now if you can, because no one knows what the future holds. It might not be available in a year. But if you get it now, it should still be valid for 5 years even if they end the program.
This is infact the best way, and what most immigration offices recommend you to do. Just leave and return. Every single time you enter Thailand during the validity of your visa, you will get a new 180-day entry stamp. Make sure you have your DTV printed out and give it to the immigration officer along with your passport.
If you immediately start the 65,000 transfers when you get your non-O visa, and then continue them through the entire first year extension, you can switch to using that for year 2. But you would need to leave the 800,000 for 3 months after that first extension and never let the balance drop below 400,000, while also doing the monthly 65,000 transfers.
As far as immigration concerned, there are only 2 kinds of ED visas.
1) Formal education, for university students seeking a degree. These are an initial 90-day visa followed by annual extensions until you complete your studies.
2) Informal education, for language and muay thai students. These are an initial 90-day visa, followed by up 3 more 90-day extensions, totaling a year.
Whether your school is reputable or not, makes no difference to immigration. They don't know what you school you went to and don't care, they just know if you had an ED based on formal education or information education. If your record shows a history of an informal education ED, you are likely to have problems for multiple years after you have this visa. That is because it's the most abused visa type, which replaced the volunteer visa many years ago after they basically stopped issuing that visa.
During the 1-year stay of study, you should NEVER leave Thailand. Countless reports of people immediately denied entry upon returning, because they told immigration they needed a visa to study in Thailand, that studying in Thailand was so important to them they needed a visa for it, and then they left Thailand. Doesn't matter if it's for the weekend, over a holiday, or what. You are almost guaranteed to be pulled out of line and interrogated, and very likely to be denied entry. There are reports of people who have letters from school giving them permission to leave, including all relevant information on dates, etc. Immigration officers even call school official and speak to them, and still deny entry.
Once your education extensions end, you are still likely to face scrutiny if you try to return to Thailand as a tourist for multiple years after this. They see you lived in Thailand, and don't want you returning again as a tourist, as they expect you are trying to either continue living in Thailand, or trying to live in Thailand again, which you cannot do as a tourist.
You should not have any issues in getting other visas even if you have ED in your past, and you should have no issued entering on any other visa type besides tourist entries after that.
For extensions based on banked money, the balance must be at 800,000 for 2 months before you apply for the extension, and then 3 months after you receive the extension. It can never drop below 400,000 after that, and must be back at 800,000 for a full 2 months before you apply the next year. So it's 800,000 for 5 months, and 400,000 for 7 months. Easiest if you just leave it at 800,000 so you don't make any mistakes with timing and ruin your ability to qualify the following year.
a tourist visa doesn't mean anything if immigration have decided you're not a tourist. Even people on multiple entry tourist visas have been pulled out of line, interrogated, and told it's their last entry as a tourist.