We have the same unit
1) Remote Switch, is for the power inverter for the fridge to operate off of 12v battery or truck power.
2) Sound Bar, yea worst piece ever used couldn't get them to work either and the zones on ours was wired wrong.
3) Fridge, yea we thought that it is dumb to include the water filter with a fridge that doesn't have a water line run to it. The factory does have a large placard that is on the fridge but our dealer removed it before we took delivery and then played dumb about it.
Hope you enjoy your 321, we like ours so far after our dealer fixed the issues. But they made some odd choices on the design with some items.