Dave gave some great info. A couple more thoughts... you can usually find the operation manual for all appliances in your RV online. The manuals that most manufacturers hand out are just a bag of those. In your fridge you should find the model number with that you should be able to get the manual. The other thing to know about the fridge is even on propane it will draw 12volt power, I’ve read that the draw can be up to 20amp hours. So it’s something to be aware of but not a deal breaker, unless your batteries are bad.
I’m not sure on the switch, Dave could be spot on about it as he knows WW better. On my RV I have an Onan 5500 generator with a plug in receptacle like you have. Inside I have a switch that says Generator and Power Cord. On generator mode I put the plug in the receptacle and that will give me 50amp power, when I plug in at a campground and in Power Code position I have 30amp, which is really just fine for my needs. Based on the apparent size of the wires on switch (1) I would agree with Dave though, battery shut off makes sense. But you can experiment with it easily to verify that.
