Welcome! The original lube developed by the Ordnance Dept. was an 8 to 1 Beeswax/Tallow mixture. I use Beeswax and Crisco in the same ratio. Set the bullets base down on a flat tray or plate that has handles to lift it with. Melt the lube and simply dip the tray into it going deep enough to cover the grooves. Lift out and set aside to cool. If you size your bullets, the sizer will remove the excess lube and only that in the grooves remains. This lube withstands hot weather quite well, but if it gets real hot and the lube softens, put more beeswax and less tallow/Crisco in the mix. This mixture works very well in paper cartridges, especially if you make the regulation 3 piece cartridge.
If you are just banging away at the range and don't want to go to the trouble of making this lube, Maxi-Lube and Bore Butter work well, but can be messy. In the old days, I even used Javelina lube. No matter what kind you use, I don't recommend putting lube in the cavity of the bullet, especially if you keep the load in the gun for a while. A friend of mine shoots "Trash Can" Minies for target work and greases them that way, but he immediately shoots the gun after loading.
As for the powder charge, the original charge for the Springfield pattern .58 cal. rifle muskets was 60 grains of musket powder (about equal to the 2F we use today). The bullet was a 500 grain cylindro-ogee expanding ball with 3 grooves (Burton variation of the Minie'). There are several styles available today and their shape and weight will have a bearing on what granulation and amount of powder you use. For the most part I use bullets from a Lyman Old Style 575213A mold which look very much like the original bullets used in the CW. It weighs 485 grs. I've found that I get excellent service using 50 grs. of 3F powder. If you are interested in short range target shooting there are several target Minies available with thin skirts which expand quite well with charges as low as 30 grs. of powder. Recoil is reduced along with an added saving of powder. I also would recommend using RWS (German) musket caps for priming. Others may have their own recommendations, but I've never had a misfire due to these caps and I've used this brand for over 25 years.
It will take some experimenting to find what works best for you, but I hope this will point you in a good direction.