what type of visa & documents do I need?

You need a Z type. To get it, you should get the following papers: your passport, a photocopy of the passport's data page, a V.2013 application form, a recent color half-length photo, a work permit, and an invitation letter from duly authorized unit (for example, the Chamber of Commerce of PRC or the Foreign Affairs Office). The work permit and the invitation letter should be obtained through your employer.