We are flying from South Africa and need to get to Yiwu in china, I was told to go via hong kong.

How long would it take me to get from HK to Yuwi and what would be the best form of transport should we fly or go by ferry and then train. We are only there for a short while on business but would like to sight see a little too? We are going to the Fair in Yawi for industrial and tool supplies would we find what we are looking for there or would we need to contact other industrial companies? If so how would we go about it when we are in china?