I have a flight from Hong Kong to Atlanta. I switch airlines in Beijing. I fly Dragonair from Hong Kong to Beijing and United from Beijing to Atlanta. I will have to get my united boarding pass after I arrive in Beijing. I will have an Electronic airline ticket. What procedure will I follow? Will I have to go thru customs and immigration? Will I have to have a Visa for this transit flight? Where will I go to get my united boarding pass? My layover is about 2 hours? Is this enough time to make the transfer? Both flights Arrive and leave from the same terminal. I am a US citizen. Thanks so much.