Hey R&R - I scaled down your photo so it won't blow up people's screens. Try to keep the width at 800 or less.
So questions...
Good questions. Keep them coming.
The Gas setting for the fridge runs it on Propane 100% of the time. "Auto" will detect whether you have a shore power connection (or generator) and run it off electric. You can listen when it's on Auto and you shut off the generator or unplug the shore power cable: a few seconds after the you cut the power, you'll hear "snick, snick, snick, whoom" as the pilot lights your fridge.
In the power box...
The guy was wrong about the plunger switch (1). That's your battery disconnect. Always use that switch when you aren't using your trailer. It will isolate your batteries and prevent phantom draws like the alarms/detectors from draining your power. Those phantom draws will kill your batteries in less than a week. Your tongue jack will still work, regardless of the position of the switch.
That 30A female receptacle (2) is the output of the generator. You can fire up your gen and run it till for hours, but your batteries won't charge and your 110 outlets won't work unless you plug the shore power cord into that outlet.
You can see your bus bar and row of fuses there too. It's pretty easy to add more accessories there, like power for a lighted beacon on a flag pole or strips of LEDs.
That big silver box is your converter/charger. I shouldn't call it "junk", but it's not good. One of your first upgrades should be investing in a smart charger/inverter. Whether you do it yourself or have someone else install it, you want the inverter closer to your batteries (in the front storage compartment). After you do that, you can remove that stock charger to make more room to coil your shore power cord.
