That's a pretty ambitious plan! I used to work in NJ and fly INTO Newark weekly, I've also made the drive to the area (Piscataway NJ) a couple of times. I've never started a trip from Newark however.
IMO, Newark airport is in about the worst part of NJ. Most of the state is quite nice (it IS the Garden State), but the airport is in the heart of the industrial/docklands area. If I was leaving my car in that area, I would want to be sure there was security for the parking, so you would probably want to pay for parking at a better hotel. I am not sure what good hotels are in the immediate area, and there may not be many options. I was generally staying about 30 minutes away where there were good hotel options, but transportation to the airport would be expensive.
Personally, I would be much more comfortable taking one of the direct commuter flights (United and AC used to fly the route) and leaving the car at home. It's a good 9 hour drive assuming no traffic or weather, and at that time of year, weather can be a concern.
Sorry, not a lot of help and a bit of a downer too! Hope it all works out for you though!