Yes, I once had a cheap radio reversing camera installed via Cinch. But it flickered. This was not due to the radio but to the radio rear view camera. I was not satisfied and therefore pulled the cable.
Maybe a good/expensive radio rear view camera delivers better pictures? Don't know...

The unit itself has no receiver for a wireless camera. As a rule, the cameras come with a transmitter and receiver. These can then be connected via a cinch connection. So I would say that yes, you can connect a wireless camera.