The gimbal and Camera unit on the standard differs from the others in the Phantom 3 range because it also houses the 2.4g Wi-Fi radio. If you remove the P3 standard gimbal unit you will have no down link for video and telemetry.
No, the cameras are custom and run on different frequencies. If you would like to know more information about the DJI Phantom 3 Standard I just posted a cool review with a whole bunch of content.