The roller coaster at Circus Circus is a double corkscrew, double loop ride, set indoors.
The hotels and casinos are open 24 hours a day, seven days a week, they never close. If you mean the circus acts, it depends on the individual hotel.
The casinos in Las Vegas are always open.
All big hotels have Bellman services, most will hold your luggage at no cost to you. However, you should tip $2 per bag.