Well you can switch the view in and out of perspective by pressing 5 on the number pad, but you can't render from that.

To view what the camera will show when you render, press 0 on the number pad.  This will take you to the default camera, or if you have several, to the last one you used.  To use a different one, select it and hit Alt-0.

You can move the camera from any view, just select it and hit g, like any other object.  I've found it easiest to move the camera while looking through it.

1. Put the 3d cursor (y'know that thingy with the circle and crosshairs) in the center of the scene by viewing from the top (numpad 7) and sides (numpad 1 and 3)
2. Change the pivot point to be the 3d cursor (it's in the second box to the right of the drop box that probably says "object mode" in it)
3. Select the camera and hit 0
4. Hit 'g' to pan, or g+middle mouse button to zoom in and out
       Hit 'r' to rotate around the center of the image, r+middle mouse button to rotate around the scene

Edit: Woops, cross-post with nruddock!