1. owners manual will have general winterizing tips.
2. Winterize/sanitize does just what it implies. That setting bypasses the water heater, but uses the coach water pump to disburse the antifreeze. Turn it to that setting, hook a hose to it, put the other end in an antifreeze jug. Turn on the water at each location until you see the pink fluid. That makes sure antifreeze is in all the lines. Pour some antifreeze in each of the p-traps. Some people will blow the lines out, just make sure you drain everything.
3. You have a remote fill propane tank. Since you can't access the propane valve, that on/off switch does exactly what it says. It turns the propane ON or Off. That way if you board a ferry or go through a tunnel and it requires you to turn off your propane you can do just that.
4. Contact service/warranty on the website.
5. That comes from Carefree. Should be an owners manual for the awning in your material with a model number. Normally its just an end cap. mention that to service/warranty as well.