Two part question from a 1st-time international flyer...

In the midst of an AA/CX trip from the US to China, I have a 7 hour layover in LAX. I will be arriving from DFW at 4:50pm and leaving for Hong Kong 11:50 pm. Will I have to handle my bags in LAX, since the first part of my flight is on AA coded and the last two legs are CX coded? These were purchased on one ticket thru AA.com. So, I didn't know if they would be checked all the way through or if I would have to handle at some point for customs or between the two carriers.

Also, is 7 hours enough time to leave the airport to meet friends in the area for a quick dinner? We would plan to be back at the airport by 8:30 pm, giving us 3 hours to get back thru security.

Thanks for any advice.