ESD is not a concern once the system is operating. If you're going to be handling the circuit boards, then you'll have to find out if they are ESD sensitive. Over voltage can be handled by a simple voltage regulator. TVS is for things like lightning protection. If you think it might get hit by ligntning, then use it, but not for over voltage. Voltage polarity protection can be accomplished by simply using connectors that can only be plugged in one way ( ie polarized connections ) Earth conneciton is probably not needed, unless again, you're trying to protect from lightning.