If I arrive into SFO on a United domestic flight and then transfer to OZ heading to ICN, how seamless is the transfer between the two at SFO? Will UA be able to check me in at my origin airport all the way to my final destination? Will I have to go through TSA security again at SFO or can I go straight to the gate of my connecting OZ flight?

Also, I have heard that OZ may be acquired by Korean Air. Hence, does OZ still participate in Star Alliance mileage programs, code share with other star alliance airlines, etc.?

Thanks.