My 2002 has red and white wires for the battery and mine is red for pos and white for neg.
Check the individual lights for the dual power sources and bulbs. 12v will only work when there is a battery and 120v will only work if plugged into power.
You can tell if the battery is being charged when plugged in if it reads more than 13.5v.. At rest, it should only read around 12.8v or so assuming it's fully charged.
Does the stove top burners work? If so, that means at least you are getting gas to that point... The hot water tank and the furnace will all be only pilot light units and the fridge 'should' work on 120v or gas, which will be a pilot light too.
The water pump will only be 12v and you have to have water in the tank for it to work. If you hook up a hose to 'city' water on the outside, you don't need the pump. You have to make sure there is an actual "plug" in the city water inlet if you are trying to use the pump, or your pump will just pump it out there..
Sounds like you are willing to get the old RV running again.. Good luck with it, but I'll bet you are going to have to replace some old things with some new things.. ;)
Mitch