I'd contact an agent about the stopover in ICN. I did the trip and had a 3 hour or so stopover, if I recall right. There is a direct ICN-LAX and a ICN-NRT-LAX flight, so make sure you check both (if that's the routing your using).

If you're doing a ICN-LAS, then you might consider just doing the LAX trip and adding on the LAS from there. The ICN KE lounge is nice, but not 12 hours nice.