There are a lot of variables at play here that go into the final calculation: twist rate of barrel, choice of projectile, patch/felt or not, powder choice, powder load. I don't know of a lot of websites that gives you a recipe like reloading centerfire cartridges, but this
one is helpful to get started. Most ML guys will give you a starting point, what works for them, and the caution to not exceed your barrel max. I suggest searching for your rifle and then seeing what others have for loads.
As for patching, generally it will give you a tighter seal, so more pressure and more recoil. On average, I've seen patching give you a higher impact at 100yds around 6". I don't shoot patched on my conicals, and I have about a 3" group at 100. If you are shooting a ball, then you would want to shoot patched, probably with linen. Again, it is really about finding what your barrel likes, and what you can stand for recoil/retort.