Howdy Zip,
Most stages that we shoot in CAS use two single action pistols,a pistol caliber lever rifle,and a SxS double barrel or external hammer pump shotgun. That said,it's quite common for new shooters who don't have the required guns to borrow what they need from other shooters. CAS shooters are very generous and are happy to help a new shooter get started in our sport. Contact the director of a match in your area and tell him or her what guns you need,and they can usually set you up. The minimum age for shooters in my area is 12 years' old. Some clubs have a special class for younger shooters that uses .22 caliber pistols and rifles and .410 shotguns. Some folks do use blackpowder cap& ball revolvers.
Bellicose Bill