In Chiang Mai you can apply up to 45 days prior to your extension running out.

Generally you’ll want to open a bank account where you live.

For certain things you’ll need to do them at the branch where you opened your account. If that’s hundreds of miles away then that can be a pain.

Recently it’s got a lot better in that you can do most things on the phone app but you may still find a need to visit your branch now and again.

No.

You can’t get a tourist visa after entering, but as a US passport holder you would get a free 30 day visa exempt stamp and could extend that once for 30 days for 1,900 baht.

@Eirik ************

Sorry to be pedantic but the correct terminology can make a huge difference as to whether an answer is correct or misleading.

@Eirik ************

a 30 day entry is not a tourist visa it’s just a free visa exempt entry stamp, but yes you can do this with your stated plan.

Depends on your passport country. Some require a visa to enter. Many get what’s called a visa exempt entry for 30 days, which can be extended in country once for 30 days.

There isn’t a limit. However it depends on where you apply for it. Some consulates will only issue one per year from that consulate. Others may impose their own rules saying you can’t have more than X in a year.

It’s valid until your current “allowed to stay” stamp.

@Ali ***********

yes. You’d obviously need to be back before it expires to apply for the extension