How to set up a orbiting camera with zoom in the BGE? How can I zoom in and out using the mouse wheel in the BGE? And press the middle button to go move around the character? 

I want the camera to be parent to the character so that it will follow it.
One way to do this is by adding an empty at the point which you want the camera to orbit around, and adding a mouse look actuator to it:



Then parent the camera to it with &#9096; CtrlP.

For zooming, you can do something like this on the camera: