German and British Citizen multiple entry visa months

Hi, We are looking to visit china on the 4th August 14 from Hong Kong, leave china to taiwan in september for two weeks, then travel to tibet on the 3rd November till the 12th November, leaving into Nepal. I have visited china before on a single entry L but my partner hasn't visited china. Firstly, can we obtain a multiple entry? Secondly if we only get a double entry how long can we stay for in a single period.