I know the rules have changed earlier this year, but it never hurts to ask everyone along the way if you can get into First class on the 3/2 class plane. Earlier this year, I got into F anyway on one of two flights by asking. Don't know if that will work now, but ask at every point (check-in, club and gate). In either case, both FC sleeper and old C seats will be completely adequate - much better than coach. I'd perfer the sleeper seat on the return anyway.
Food is good too.
Sorry for you loss, glad you got the seats.
You probably have places to stay, but the Hyatt at INC is absolutely wonderful.
I'm sure you know your way around Seoul, but INC is not as near as the old Kimpo, but there are several options for getting into Seoul - I usually take the bus to a nearby hotel where I want to go.
Billy