Most rental companies also want you to return the propane tank full and the waste tanks empty or they will charge you to do to do it for you.
Battery...Here are some quick and basic answers in laymen terms. Yes. You will need to charge that battery sometimes daily with 4+ people unless you are hooked up to power at a camp site. You can charge the battery sufficiently by driving/idling for 30-60 minutes, by running the generator ( basic charge in 6 hours on my Onan gen), or from being hooked up to shore power (camp site hook up).
Fridge....needs propane to cool off and takes several hours to do so. This is not your house fridge. Can run on shore power or the battery. Most need to be pretty level to work or you have no fridge. Rental units generally don't come with levelng blocks. Small 2x4's work nicely in a pinch. That said, the fridge could run for a few weeks (on low) and never drain the propane.
If you run the furnace too hot the blower/fan will run continuosly and eat the battery dead in a few hours. That means you wake up freezing.
Like Mitch said, conserve and plan if you aren't hooked up. Turn off lights. Don't run the hot water heater until you know you will need it in say 15 minutes. Take navy showers.
The genorator....usually not free. It will run the microwave and/or the ac when it is running as well as lights etc...Don't open windows when it is running, The gen uses the gas from your engine/chassis. Mine uses about a gallon an hour. When the gen is on, maximize your power. Now would be a good time to plug in and turn on a small electric heater if you need it. Good time to cook with a microwace or run the ac if needed.
Toilet chemicals....you may ned to buy some.
Dumping...best to watch some how to videos on you tube. Those were a big help for me. Buy some disposable rubber gloves. Take your time. Don't rush this part even if you have people behind you. They will thank you later if you take a little more time and don't leave poo all over the place. ;)
Ask other RV'ers. I have found all of them to be pretty nice people. They were all new once too and they all seem to like to help the newbies gladly. Just ask! :)
