Fly is your only option with 2 land crossings.

Air Asia. CNX to KUL

VOA cannot extend (7 day "extension/denial" does not count as one)

If you plan on staying for 60 days, obtaining a tourist visa is actually cheaper and a bonus of not dealing with the immigration office at all.

The south korean citizen does not need to do anything.

Some immigration offices are open for that purpose. Otherwise Monday

Usually new passports (with no stamps) attract attention by any border officers. Because it shows you are trying to hide something or may be not a genuine document, so they look deeper and tend to do more investigation and see if your story checks out.

They are just asking standard questions that any border officer would, don't feel offended. i.e. What do you do, why do you visit, how long, etc

Same day you get the visa if you wanted to. It’s one working day. Apply first day, collect afternoon next day.

The best Thai consulate in my opinion is still Vientiane. They take Thai baht so no need to exchange currency. Right next to Thailand so you can go back the same day even. You can take the bus from the south bus station to the friendship bridge for less than a dollar.

Theres a few caveats but workable.

1 ED visa every 12 months. Have to make an appointment, which actually makes the consulate run more efficient.

You won’t be asked for onward travel by anyone. Because it’s not something that’s expected

6 months at a time is ok as a tourist visa as you no need to park 800k in a bank account.

But ultimately depends on what your goals are though. If you see yourself travelling frequently in the validity of the period in Thailand I would go get a METV.

As long as you don’t do more than 2 land borders a year on exempt