For an Enfield Rifled Musket, ffG should do for powder. Yes, black powder DOES produce fouling- part of the reason for using grease on the bullet is to help keep that soft. For the love of heaven DO NOT use smokeless powder- EVER- in your muzzleloader. That way lies death and injury to innocent bystanders. You CAN use black powder substitutes, such as Pyrodex Rifle, Triple 7, etc. They substitute VOLUME for VOLUME, not weight for weight. Me, I love the smell of sulfur in the mornings. Swab the bore every 5 shots. no worries.
DO check the caliber of the Minie balls you need- and Track of the Wolf (among many others) can get you what you need.
Grease- well, I prefer the skin oil collected from from 18 yr old redhead virgins during a full moon. The exact composition of what is best has been the source of argument since the mutiny of the Sepoys in India over the lube on their cartridges (If that went over your head, do a Google search- interesting bit of trivia in how to destroy your empire) Frankly, I shoot a .50 Hawken and use Bore Butter, and when I'm out, I use Crisco. You can try melting (in a double boiler so you do not have a NASTY kitchen fire) beeswax cut with Crisco.
Cartridges? Well, I roll my own for a .50 and a .45 Pennsylvania, using JOB Double Wider rolling papers. Roll around a wooden dowel equal to bullet diameter, lick, smooth, let dry, slip off. Slide over base of bullet, tie with a COTTON thread, fill w/ powder, fold end over, drop of glue. Have seen original cartridges that were rolled from newspaper.