Is this just a webcam with wheels attached?

Dunno what it is.

Question 2, does placing a cardboard box on it constitute assault

If the cops see you doing that - you’re lucky if months later you don’t wake up from a coma after they beat you into unconsciousness for “resisting arrest” and after that - you get indicted for a couple felonies. Which ones? Whatever the testilying cops come up with.