Questions for Curt Echo Mobile Trailer Brake Controller - 7-Way - Bluetooth Smartphone Connection

Yes, it is bluetooth not wifi

Yes, this is powered by the vehicle through the trailer light hook up

Yes

Reverse polarity protection is an internal circuit that ensures that the device is not damaged if the power supply polarity is reversed. Short circuit protection is protection against excessive currents or current beyond the acceptable current rating of equipment

This is an electric brake controller so it would replace any other controllers you have installed

This does not hook up to any batteries. It will go directly into your power port on on the vehicle and the trailer wiring will hook up to the Echo. There will be a complete circuit from the battery to your trailer.

As long as you can download the app to your vehicle.