About the water heater: Since it's been sitting in a field for so long, there's a good chance that the burner tube, orifice, and pilot tube all need a good cleaning. Apply some rust penetrant on the sheet metal screws that hold all those pieces together and take them out. Compressed air will do a good job of cleaning most of it, you may even find a spider nest or two in there. After it's cleaned, fill the propane lines by lighting the inside stove until you have good flame. Try to light off the heater. It may take a while to purge the air out of the propane lines. If the heater flame won't stay lit, you may have a thermocouple issue. Those are cheap to replace.
Good luck and have fun on your first trip!
