90 days. It's a regular tourist visa. Look into other options such as education visa, volunteer visa or work permit. In pre-pandemic times with a visa run you could get one more 90 day visa. Unfortunately, it's not an option right now. In a nutshell, a month before your allowed 90 day stay runs up, reach out to a language school or a visa agent. If you can fork out 20 grand, Elite visa might be an interesting option
Get Elite Visa or look into ED and Non O one year visas via a language school or an agent. That might be a good option as a way to see if you like it here before committing for a 5 year Elite at almost twenty grand
Quarantine is still a requirement. No matter what. Will it be lifted or shortened for vaccinated arrivals is yet to be seen. Don't expect any changes to that policy till like June as earliest