UA to TG Transfer at ICN?

Question about a UA to TG Transfer at ICN.

I assume it is like NRT. Land. Re-Clear transit security. Board TG flight.

I notice that there's two OZ lounges in ICN. Will I be able to visit either of them easily (while in transit)?

Also, is there a transfer desk? Just in case UA isn't able to issue my TG BP.

I'll be flying on an award ticket (issued by UA). TG used to require the credit card used to purchase (pay the taxes) to be presented at check-in. Anyone know if that's still the case?

Thanks!