RWS Dynamit Nobel 1075 caps. Simply the best IMHO.

Powders, up to you.
Substitutes can be had at local retailers.
Hodgdon 777 FFG is very good in a sidelock as is Black Mag'3. Not a Pyrodex fan, I'd much rather shoot traditional black.

For traditional back powder Swiss is the supreme powder in my view. Goex is also very good. I've heard that KIK is good as well. Where I purchase my BP:
http://www.powderinc.com/

Good Luck!

Tahquamenon