I've never used pellets, can't see spending the extra money for less loading flexibility, prefer Goex if I could get some, use T7 cuz it's easy to find.
You don't need a lot of cleaning supplies, use old T-shirts for patches cut 1½"-2" square, his #11 caps will work, but you might as well buy some of your own, they aren't expensive.
At the range I just wipe with a spit patch, there are many cleaning concoctions, water works about as good as anything.
You will need a .50 cleaning jag which will double as a loading jag for the powerbelts. That needs to fit the ramrod you end up with, make sure the threads match, it will be 8x32 or 10x32.
Pick up a bronze or nylon(Tynex) bore brush of the approapriate thread size, too.
You'll need a nipple wrench or use your Dad's.
Tim