Welcome to the forum.
As far as an good intro, this is the place. Before long, you will have four responses to your original post from guys who take this stuff very seriously.
My experience with muzzle loading long arms is minimal and not contemporary but I will venture a guess you will need number 11 caps. They can be bought at a Cabelas or Bass Proshop store.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson