Why not doing something simple, like that :
- Mouse wheel in => Zoom in.
- Mouse wheel out => Zoom out.
- Some key + move the mouse => Rotate the camera around the "point of view".
- - Mouse move up, the camera move down.
- Mouse move down, the camera move up.
- Mouse move right, the camera move left.
- Mouse move left, the camera move right.
And, by the way, i don't like how the angle change when i zoom, with a stop at the change.
Oh, and can we have a more powerfull zoom ? I mean, it's hard to test how look my models in-game since i see then from so far