Oh, man, are you gonna get bit bad. You're going to love shooting the Holy Black Powder.
Okay, I think 35 grains is the max. recommended charge for your .44 (someone will come along and correct me if it isn't). I confess I don't measure for my revolvers. I fill up a small scoop and pour the powder in up to about 3/16" from the top of the cylinder, put the ball on and ram it down.
Best sources of lead is plumber's lead or roof flashing. You want dead soft, i.e., pure lead.
How the caps fit on the cones (the tapered part of the nipples) is important. Get No. 10 and No. 11 size caps, preferably RWS (German) ones. Figure out which ones fit best when you gently push it down onto the cone. You want a tight fit that needs a bit of encouragement.
Once you know which size is closer to a tight fit, remove the nipples and chuck the threaded part into a variable-speed drill. Slowly grind down the cones with fine sandpaper, emery cloth or a fine file. Remove very little at a time, just a bit more than if you were polishing it. Try a cap on it. You want the fit to be snug, not tight. Keep polishing it until you get the cap to fit snugly. Rinse and repeat for all the nipples.
If you're going to shoot it a lot, I recommend getting a set of Treso beryllium alloy nipples.