Yes Yellowstone National Park Campgrounds that have RV sites do have electricity, water etc for you to hook your RV up too.
The campgrounds do cost money and the cost for camping in an RV site campground at Yellowstone National Park depends on which campground you go to and what RV site you pick.
Camping in a tent can cost as much as $40.00 per night and an RV parking there in an RV spot can cost $45.00 to $55.00 per night.
There are several different campgrounds in Yellowstone national park that you can choose from so it's best to get a reservation first so you know you have an RV spot to park in.
I would recommend staying in Yellowstone National Park for at least 2 days to see all the park so I would go to one campground for the night and then travel to another campground in the park for the night.
The Yellowstone National Park pass you buy lasts 7 days for $25.00 but you can buy a yearly pass for $50.00 if you want too.