Sorry to hear about your shunt problems. It's ok to have increased protein in the CSF becuase of the presence of hardware, but not ok to have an infection. To answer your questions:
1.Infection, bleeding, tumor, overproduction of CSF, occlusion of the tip of the cathether, and shunt malfunction-common (intrinsic to the hardware).
2.I have seen patients with multiple revisions, but I don't think there's an exact number. It depends on what's wrong with the shunt and where the problem is. Of course, if it's infected, the whole thing comes out.
3.Can't answer that. You'll have to talk to your neurosurgeon.
4.Yes, nothing in medicine is 100%
5.The endoscopic procedure is the standard technique in most places right now. CT guided stereotactic surgery has also been done, but you'll have to talk to your neurosurgeon about his/her particular approach and their personal complication rate.
Good luck