I'm the owner of a Class B, but it's not the class of RV that makes a difference here; you'll need to check with the owner of the RV you're renting, to understand their policies.
In general however, propane is a minor expense and is only needed when you're not plugged in at an RV park (except for cooking, if you use the stove). Everything else runs on shore power.
Electricity is not metered; the price you pay for the site includes electricity, water, and using the dump station.
Ask the owner of the RV what you can expect for gas mileage, to estimate fuel consumption. If the tank is full when you pick-up, you should be sure it's full when you return.
Does the owner require you to clean the RV? Some owners charge a cleaning fee automatically, but it's a good idea to ask if you can avoid the cleaning fee, if the RV is returned in the same condition as when you picked up. Avoiding spills in the refrigerator, covering any food cooked in the microwave, and sweeping the floor regularly, along with removing all trash, will help minimize the need for "deep" cleaning.
Don't flush anything but single ply TP down the toilet, and use enough water with each flush to clean the bowl and keep the bathroom smelling fresh. Again; confirm policies and expectations with the owner before you leave.
There may or may not be a charge for sales tax in addition to the rental cost, depending on the laws in your state.
You'll pay a 10% service fee to Outdoorsy (the owner also pays), and coverage for Roadside Assistance (highly recommended) is also available for a cost of $15/day.
If you haven't already made a reservation to confirm the dates with the RV of your choice; that's the most important thing to do. (Some RVs are booked months in advance.) Then you need to plan your itinerary, and make reservations.
Happy Trails to You!