The gun is a generic type shotgun, but reasonable to the late percussion era. Blackpowder will work well, but because it is a percussion there is no reason you can't use Pyrodex, Triple 7 or any one of the other currently blackpowder substitutes. These powders have the advantages of being more readily obtainable than black because black is classified as an explosive and requires additional licensing which few local stores have. As far as corrosiveness, black is actually less corrosive than pyrodex and most of the substitutes. Shot was carried in a shot snake and probably just about any other container useable in the field. Powder was carried in horns and in various copper flasks somewhat dependent on the resources of the user. I use premeasured charges in individual ready containers. Typical loading method is use the same volume scoop for your powder as would contain your shot weight. In a 12ga start with an ounce of shot and the same volume of FFg will give you approx 72 grains of powder. FFg is usually recommended by manufacturers because it produces slightly less pressures. However among the competitive muzzleloading shotgunners FFFg is probably more frequently used and your gun will not be endangered by FFFg in same volume of powder for volume of shot loadings. Other items you need will be some overpowder Nitro card wads, a cushion wad usually helps and an overshot wad to keep your shot in place.
There are quite a few safety and loading techniques you need to know so don't just blunder afield. Contact your local National Muzzleloading Rifle Association field rep and find out where you can get the instruction needed. You will have a much greater probability of success with much less probability of injury. These firearms lack most of the safety features you associate with modern firearms so your real safety is dependent upon proper knowledge of the issues. Too lengthy to discuss fully here.
