While I don't have that particular rifle, in answer to your powder question, I shoot GOEX real black powder. Real black powder ignites at lower temperatures than Pyrodex (I don't know actual temps. but the differences are considerable), and from what I understand, it burns faster. It's a big deal for flint and cap lock shooters because generally, they don't produce enough heat from the sparks or caps to consistently ignite modern substitutes. Pyrodex works well in modern in-lines because they use a shotgun primer (which is a much hotter prime than blackpowder/flint or caplock) and it's much closer to the main charge, generally speaking.
If your CVA is a side-lock, I'd recommend the real thing because, all things being equal, it'll be more reliable than Pyrodex in that type of gun. It does require more clean-up, it's harder to find, and it's more expensive (that seems like a lot of disadvantages), but it simply seems to work better in traditional guns (and after all, if a gun doesn't work reliably, then what's the point?). Can you tell I'm a bit of a snob about powder choice? :money:
Anyway, that's my $.02