You can purchase Triple Se7en powderin loose or pellet form. I suggest getting the loose form. Its not as expensive, and you can custom your loads better. Pyrodex RS powderis an excellent powder also.

The Windex is for swabbing the bore of the rifle between shots. For the best accuracy when you sight in, dampen a patch and swab the fowling out of the bore. Then run a couple dry patches down the bore to make sure the bore is dry, and load as normal. I suggest when you swab, only work in three inch sections at a time. It will help from keeping the swab from getting stuck in the bore.