1. Most of the wiring to the rear runs down the drivers side under the door.
2. Just what you said, try to keep the exposed electronics dry.
3. 30 or 40 bucks and your time to herculine your tub, I did it and its great!
4. Just use a 3/8 drill bit and drill a hole where the drain plugs stop bailing water.
Hope it helps. The herculiner is real easy to take care of and clean. Add some waterproof seat covers and your good to go.