The best suggestions you have received so far have been to GO SHOOT SOME GUNS. I don't know where you live/work/shoot but if it's Winter there, you have a couple of months to think about it. If your in a place of warmth and year-round shooting, may the fleas of a thousand camels infest your arm pitts.
You also mentioned BP. In the same thought line, cartridges. Why would you need suppositories?? Get together with some Cap Gun shooters, learn the basics and ........ get yourself on the Dark Side.
Don't worry excessively about your first set of guns. They won't be your last by a long shot. This game is addictive. Resistance is futile. You will be assimilated!!
Coffinmaker