How long or how many days does it take for the visa department to issue a visa?

How long or how many days does it take for the visa department to issue a visa? I planned to stay in the Macau and China a total of 15 days. How does the visa works? Can I use the same visa on and off during my stay or it is only good for one entry?

Apart for the application fee, passport, what other documents are required?
Are photos requires and what size?