You can add multiple cameras to your 3D Comp, but only one of their views can render at a time. From the Comp window's 3D view menu, you can select any camera you want to look through while you're working, but only the Active Camera will render. So how do you make a specific camera the Active Camera?
By placing it on top of the layer stack. The highest up camera will always be the Active Camera. If you want to cut between two cameras, place the first camera on top, but make it end partway through the Comp's duration. (Drag its out-point to the left, so that it doesn't extend all the way to the end of the Comp). When the first camera-layer ends, it will no longer be the topmost camera; the next camera down in the stack will become the Active Camera.