What monitoring system do I need: professional monitor or standard TV?
If you use 1 camera, a simple TV (which has RCA video input) is definitely recommended. Even for more than 1 camera, if you use combiner like quad splitter or switcher, a TV would be fine. But, for special features like slave video output (to be connected to additional monitor), alarm systems or for packaged observation systems, you may need professional CCTV monitors.