I recommend the stabilizer, and we bought the aluminum version because of weight. As to your water heater there is a switch on the lower left hand corner on the outside that also needs to be turned on. Once that is on the inside switch will control it. The water filter is located behind the small wood access panel in the front storage compartment right behind the utility panel, you need to remove two screws.
Sounds like your dealer didn't do a very good PDI. They should have shown you the filter and water heater switch.
PINNACLE 2015 38FLSA. aka: "Roam Sweet Home"