Beijing Airport Transit

I will be traveling from Rome to Hong Kong on December 26th, and I have to transit at BJ airport.
Then I will flight back to Rome on January 3rd 2014.
My flight schedule is given below:

FLIGHT 1:

CA940 Air China 19:50 12/25/2013 Rome - 13:20 12/26/2013 BJ

CA115 Air China 15:30 12/26/2013 BJ - 18:50 12/26/2013 Hong Kong
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FLIGHT 2:

CA118 Air China 8:30 1/3/2014 Hong Kong - 11:45 12/26/2013 BJ

CA939 Air China 13:30 1/3/2014 BJ - 17:50 1/3/2014 Rome
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In both flights, I would like to know if I have enough time to pass the security check at BJ Airport.
Is it the transfer at Beijing Airport in the same Terminal?
Is it international or domestic the flight from BJ to Hong Kong?

Thanks for Your help
Best Regards
Andrea