I'll tackle a couple of these with which I have first hand experience:
1. There is a rocker switch that has been installed by PC on the lower dash immediately to the left of the steering column. It seems to activate something under the hood. Is this a temporary transfer switch to start the vehicle with the coach battery in case of failure of the chassis battery? That is the only thing I could think of. What is this switch?
Barry is correct: The white rocker switch is NOT an emergency start switch. It is used to boost the engine battery using the coach batteries. Put the ignition switch in the accessory position just before the start position, then press and hold the white rocker switch for a count of 30 (about 20-25 seconds - I count fast). Release the switch, then turn the ignition switch to start, and the engine should fire up. This may need to be repeated a second time, if so, wait five minutes. I've never gone past twice.
Some models may work with the generator running and charging the coach batteries. I'm pretty sure that's not the case with the older models with different inverters. I haven't tested this. Yet.
And FWIW, a word of caution based on personal experience: don't forget to turn off the lights in the outside compartments; I have one in the side rear compartment, and the macerator compartment. Also the wardrobe closet. That's why I have personal experience with the white rocker switch.
5. In regard to the refrig, I assume with these two ways (I have not had anything but a three way) you just run down the road on gas like the trailer folks do. Or, just keep the doors shut for a short trip and keep the thing shut off. That is not an option with my wife!
Again, different models/years will result in slightly different responses.
The refrigerator should automatically switch to propane when disconnected from either shore power or generator power, and switch back when one of those is operating. In my 8,000+ miles over the past 13 months, it has worked flawlessly, except on two occasions: once when the sensor at the back of the refrig went gunnybag, and once when the propane dealer forgot to turn on the propane at the tank -- I now monitor that personally.
So far we haven't forgotten to turn the house disconnect switch back on after refueling. I'm sure that day will come for us.
I've also seen recommendations that the switchover after disconnecting from an AC power source should be checked to make sure that it has actually switched, but I frequently forget to do that also, but so far it hasn't caused a problem.
Welcome to the forums. We had absolutely no experience with RV'ing prior to getting our 2008 2551 13 months ago. No RV, no trailer, just some tent camping 30+ years ago. These forums were our primary source of education on the functioning of the PC, and a major source of RVing in general. The search function on this site works extremely well (in most cases).
Make sure you set your preferences to monitor the forums so that you'll get an email notifying you of new posts. Invaluable.
Hope this helps,