Looks like you got some real good info already but I would like to ad one thing about this. Check for local BP clubs in your area . Sometimes you will find them on the net with a little searching or you can call your local supplier of powder and balls. He will know about the local clubs and shoots that you can attend. Most of these guy's are more than happy to teach you all they know and If you take your gun to the range where they shoot most will be happy to show you little tricks and tips to get the best from that gun. Don't be afraid to introduce yourself and ask for there help, they will be happy to meet and help another BP shooter.
Be careful, Black Powder can be habbit forming and drive you nuts, Just look at the guy's on here!,
Mike