Cost of China visa and visits to neighbouring sites.

We will be travelling to Guangzhou for the second time in Dec 2013 for 11days. We wish to move around the neighbours such as Senzhen, Zuhai, Hongkong, etc. Please advice on how to move about. As such we have to apply for multiple entry? What is the cost and duration of it? Because we will be travelling to Beijing in Feb 2014. Thank you.