I am currently holding a *A F award from Washington to Bangkok using US miles. I'm flying on UA, TG, SQ, and NH. I originally had a C award, but had it upgraded to a F award. Thus far (5 days now), they haven't debited my account yet the 30,000 extra points, however they did reissue the ticket with the new routing. Any idea if that will lead to a problem for me? Will I show up to the airport in late December and have them ask me for multiple thousands of dollars? Anyone have any experiences with this?

I also am still in C on one of the legs of the trip (ORD-LAX on UA). If I can't get it to clear into F before day of departure, can I standby for F that day?

Last question: I have a long layover in NRT on the return. It's about a 10 hour layover. If there is one (I don't know if there is or not), can I standby for another flight either on NH (the airline I'm currently scheduled to take) or another *A airline?