Connections at Guangzhou Airport

Hello. My son is flying from Bangkok to Guangzhou on China Southern. He arrives at 7:30pm and then has to catch another CS flight to LAX at 9:30pm. The flights were made independently of each other so there are 2 different itineraries. Can anyone tell me:
1. Will he have to go thru customs when he arrives from Bangkok?
2. Is 2 hours enough time to make his flight to LAX?
Assuming he has to pick up his bag and then check-in for the LAX flight, am wondering if he should take an earlier flight?
Thanks.
GD