I have been successful applying for a retirement extension at Phuket Immigration as early as 45 days before the expiration date. However, I have never had an appointment, I just show up early in the morning.

A Non-O visa can be extended annually in Thailand just like the Non-OA. The big advantage of the Non-O is that there is no insurance requirement. I've had only one Thai visa in my life, but have lived in Thailand legally since 2012. I do the 800,000 baht in the bank method to qualify for my retirement extension but if one wanted to they could do the 60,000/month income method.

My understanding about the Elite Visa is that you have to pay 1,900/baht year for an annual extension of stay if you do not leave the country (leaving -- and returning to -- the country in the time of covid is problematic). Also, unless you live in Bangkok I think you have to do your own 90-day reports.

I do my 90-day reports online. Takes about 5 minutes. I can't imagine people making huge financial decisions based on doing 90-day reports. If online isn't working I can do it by mail or in Phuket at the drive-in window at immigration. Worst case, even if you never do a 90-day report and you are caught the fine is usually 2,000 baht (5,000 baht if they think you are doing it on purpose); there is no consequence to your continued ability to get annual extensions, you won't be on overstay. Do it when you're supposed to (about 3 times a year, typically they do a 90-day report when I apply for my annual extension of stay) and you don't have to pay anything.

If you qualify for a retirement extension by being at least 50 years old, then my cost for an annual extension of stay for the purpose of retirement is 1,900 baht. Plus 200 baht I pay to my Thai bank for documentation to support my application. If I want to leave Thailand I can withdraw my 800,000 baht and take it with me. The 500,000 baht paid to Thai Elite is gone.

When you entered Thailand on an OA visa you should have received an entry stamp with permission to stay until one year in the future. That permission to stay doesn't disappear when your OA visa expires, just your ability to leave the country and re-enter the country using that OA visa without needing a re-entry permit. After your OA visa expires should you wish to leave and return you would need to purchase a re-entry permit. However, no foreigner (with very specialized exceptions) can enter Thailand at the moment so it's a moot point.

To answer your question directly you should be good to stay until next January (you should have an entry stamp with this permission to stay stamp in your passport). Should Thailand open its borders before then and you want to travel and return to Thailand you will need a re-entry permit and meet all the additional qualifications there may be in place at that time (health certificate, mandatory quarantine period, etc.)

Yes, I believe immigration officers approve batches at a time when they are not busy doing other work. It may take a few days.

If instead you wish to get an annual extension of your Business Visa you might look at the requirements here:

For the 30-day Emergency Extension you might look at the requirements here (these are the requirements for extending a Tourist Visa, but will probably be similar for extending a Business Visa):

Turning on notifications for this post in the upper right corner of this post (click on v) will accomplish the same thing.

Here's an easy way to remember this: the 90-day report is due when (and only when) you have stayed in Thailand for 90 consecutive days. The counter (re)sets to 1 when you enter Thailand. Each day you stay in Thailand the counter increments by one day.

If you are in Thailand on the 90th day the report is due and can't be avoided by leaving Thailand. You do, however, have 7 days after the due date to file your report in person. If you leave before the 90th day no report is due and the counter will reset to 1 when you re-enter Thailand. You can file in person up to 15 days before your report is due. You can file by mail before the report is due if your immigration office allows. You can do the report online but only during the window from 15-7 days before the due date (90th day).

Use these two tools and you'll be fine if you have sufficient patience. Google Chrome browser will do automatic machine translation of Thai text into English. Google Translate phone app will do machine translation of images containing Thai text into English when you use your camera to take a picture of the image. Machine translation is not 100% accurate but when you have context you should be able to figure out what information they are looking for and what buttons to press.

If you really have an ED VISA rather than an "extension of stay" for purpose of education then you can't transfer the visa from your old to your new passport. You just need to use both passports, the new for everything except for your visa, the old only to show your visa.

If you have an extension of stay stamp you can get your local immigration office to do the transfer from your old to your new passport. They will probably want to see the letter you get from your country's consulate and the service should be done for free.