split screen

How can I use my camera’s output for 1/2 of screen and use my pc for the other 1/2 of the screen on a monitor?

Look at the bottom of this page, there are precise instructions on how to do this.

http://unity3d.com/support/documentation/Components/class-Camera.html

And then there things on the unity store you can use to output the camera on your computer to a camera in the game.

Use the Normalized Viewport Rectangle option in your camera and define a certain portion of the screen (i.e. 1/2 of the screen) that the current camera view will be drawn upon. Then you should add a guiTexture and overlay it on the other half. Use built-in WebCamTexture and assign it to the gui texture.