I'm going to be arriving in Beijing from Hong Kong on a China Southern Airlines flight which doesn't come into Terminal 3. However I wish to stay in transit to go on my following flight to the UK which is with Emirates and from Terminal 3. Is this possible?

Also, my friend is coming from Beijing and coming on the same flight with me. She will be bringing me more luggage to bring on my flight to the UK. Is there any chance I can collect this without going through customs?