Apply for F study visa

I am a student in China with my wife from Saudi Arabia
i am going to register representative office in china in Guangzhou and doing my business beside my study
the lawyer ask me to apply for F (usiness visa and right now i am holding X study visa ,
is it possible i use my X study visa vaid till 2012/12/15) for my own office or i have to change it to F business visa or can i hold both visa in same time or may i apply for F visa in china or Hong Kong or i have to back to my country and apply for F visa from china Embassy from Saudi Arabia ...