Type of Visa for Canton Fair in Oct 2011

I will be attending Canton Fair between 16 to 19 October, 2011. After the event, I would also like to travel to Hong Kong and return back to Guongzhou. What type of visa should I get for this whole trip (Guongzhou - HK - Guongzhou); Business Visa or Social Visit Visa?

What will be the weather then? What is the average price for food in Guongzhou and Hong Kong?