Korea has its own digital arrival card AND electronic travel authorization called K-ETA, but most people don't need it. It's nationality based. And if it's a connecting flight, you don't need it either.
Thailand DTAC is mandatory for everybody (non Thai passport holders), for each entry.
No, not yet approved, and very likely it'll be rejected as you're supposed to do the first always offline. Either way, they'll send you another email later saying whether it was rejected or approved. If approved, then you don't need to do anything else.
No, I'm talking about DTV. The Embassy website literally says to do not ask a DTV if your intended entry is beyond 3 months in the future. As a matter of fact, you can see here people who wrote their applications were denied because they applied like in August or September for soft power courses starting in January.
why? 🤦🏻🤦🏻🤦🏻 because that's what the official embassy website says. So, you'll need to deceive and tell them you're coming within 3 months. Not a good start for a visa.