Interesting about the Seoul consulate.

Doesn't matter which embassy you go to. But you have to leave. Don't forget to get cancellation papers before you exit.

If you're able take the 20 year one. The 5 year one is cheap and an easy temptation, but you should aim for 20 years as the per day cost is lower.

Advantages: less paperwork. no bank statements period. This is useful for those who have high networth but the majority of funds are locked up in other assets or in company they control . You just pay money and that's it. No need to tell where you got the money from, if you have the money you pay it and it's settled right there.

Disadvantages: no working so you must have the means of generating wealth (ideally you are an investor)

Cancellation is free and needs to be done at the immigration office (not airport)

Wonder how they deal with the issue where some places do not take payment online or just take a small online deposit (which can still be refunded or used as credit) and prefer cash payment for the balance when they check in

Neighboring countries can cross as many times as they like, and can also enter using their ID card (with some restrictions).

The countries also let Thais do that too (I know Laos and Myanmar do)

You get stamped out at Chiang Mai if your international flight is on the same ticket.

10 usd is cheaper. Like enough savings to get you 1 good western meal or 2 large beers.

Are you on a visa or extension of stay? There's a difference

go get a few crispy usd bills from superrich before you go