Burlmart, I have the 213 also. Your water heater access panel is on the driver's side. Open the cover by turning the little ring thing and you will see the tank. There is a plastic plug near the bottom that you unscrew, make sure the faucets are open and it will drain down to about a gallon, so nothing to worry about volume wise if there is a freeze. Use some teflon tape to reinstall it. I have heard that after a few drains the plug should be replaced. I'll believe it when I see it. I haven't had trouble with water being in the fresh tank for a long time.
The best way to handle the fridge is to get it cold by hooking up to your house electric the night before, put all cold stuff in there, and then switch it off while on the road. The gas setting uses a flame, and many people seem uneasy about a flame while driving. We have gone for 7 hours so far between hookkups and the food has been fine.
As for the hotwater heater light, who knows? Dario and I have figured out that it comes on if the heater, in gas mode tries to start but can't get a sustained flame. Thats just our not so humble opinion.