If you're looking to study on the islands you most likely will be paying 20,000 baht to switch from a tourist visa to an ed visa. I live on Samui and just went through this process. I also spoke with a few different schools on the island and found that it is the same.
I am in Samui, had a stamp that said something about a 90 day report, so I ask when I went in Wednesday and she said no need to worry about it. But as mentioned above every IO is different and can vary!
AXA is a worldwide insurance I believe.... but I could be wrong... I know they've got offices here in Thailand and Robert is a broker in Bangkok. They'll cover you if you test positive for covid with or without symptoms, whereas some insurance won't if you're asymptomatic. Robert has also been great to deal with, super helpful. I was in a motorbike accident about a month ago so I've already got a claim sent in haha.