I'm a newbie to this and haven't even bought a pup yet, just getting the itch. I'm wondering about the brakes. I've seen reference to checking the pads, so I assume they're disc brakes similar to a car. But are they hydraulic, or electric? If hydraulic, they don't plug into the towing vehicle's hydraulic lines, so there must be a reservoir for brake fluid somewhere? Would it be a dumb question to ask a seller where the brake fluid is added?