I am going to be discussing the furnishings and fixtures of Class A motorhomes. Some will vary mildly from what I am describing, but the vast majority of Class A motorhomes will be exactly as described.
Motorhomes are designed to be operable both independently or hooked up to utilities. The one I personally own is 30 years old, the newer ones look a lot nicer, but still operate the same way, even the brand new 2005 models.
Motorhomes will have a water tank underneath that can be filled
up with fresh water. Some models have tanks rated for drinkable water,
others don't. Your motorhome will have a water pump that can be
turned on from a switch on the inside that will provide water pressure
to all fixtures. Your motorhome will also have an outside water hookup that hooks up to a normal hose. When this is hooked up you will have water pressure all the time. You should always use a heavy duty hose, as cheaper hoses will start leaking soon after being hooked up.
There are two holding tanks for dirty water. One is the "black water" tank,
and it takes water from the toilet. The other is the "gray water"
tank, which catches the water from the shower and sinks. These
normally have to be emptied manually, but if you are in a place with a
permanent sewer hookup then you can just leave the dump handles open
and let it all drain in there. Both tanks will have an indicator
inside the home showing how full they are.
You will have a hot water heater, it will be very small, and has to be
turned on manually. On older models you have to go outside to turn it
on, on newer models it is done from the inside. It holds just enough
water for one shower. But it heats up the water really fast. It only takes a
few minutes. Most motorhomes will have propane ones, but electric ones
do exist.
Now for the electricity. Your motorhome will have a gas powered generator capable of
providing enough power to run anything you might have plugged in. Your
motorhome can also be plugged into an electric outlet and get its
electricity from there. Newer ones will also have a bank of batteries
and an inverter giving electric power even when you aren't plugged in,
and the generator isn't running. Not all older models have this
feature (mine does not). All the built in lights will be 12 volt and
will run off the RV's secondary battery. The secondary battery is constantly being
recharged whenever you are plugged into electric, have the engine
running, or have the generator running.
You will have one or more propane tanks under the RV. These
provide the gas for the hot water heater, stove, oven, furnace, and
catalytic heater. The refrigerator is also capable of running off propane as
well. Mine has two tanks, apparently that is fairly standard.
The refrigerator will be fairly small. They are bigger than a dorm unit, but much smaller than a standard sized home unit. They can run off either electric or propane. These do not get nearly as cold as what you are used to. The freezers only barely get cold enough to make ice, and you should generally use things stored in the main unit rather quickly.
The oven and stove will almost certainly be propane, electric ones do exist,
but they are mega rare due to the fact that most RVs and RV parks are
only equipped for 30 AMP electrical services.
Newer models will have a cable TV hookup built in, older models will
likely have been refitted for this feature years ago (mine was). I have seen a lot of people out in the State parks who even have a satellite dish setup.
If you just want an RV for temporary
living I would suggest getting the oldest and cheapest functioning one you
can find, as newer ones are really pricey, and they depreciate much like
cars do. You might easily depreciate a newer one $10,000 or more in
one year.
If you don't appear to need the ability to drive the thing
around then you might want to look into getting a "5th wheel" RV
instead. Its the same thing as what I just described except it does
not have an engine and has to be towed by a truck, they are a lot
cheaper.