I hold (Malaysia passport) fly from Penang, Malaysia and Transit at Guangzhou Airport

(using China Southern Airline) to New York.

Transit Layoff time is 12 hours. Using China Southern Airline
1) Do i need a Visa? If yes, can i do at Guangzhou Airport? Pls advice
2) Do i allow to leave the airport to nearby downtown before catch next flight?
3) Which terminal i arrive at from Penang to Guangzhou Airport?
4) Which Terminal is my departure from Guangzhou airport to New York?