What other tools and supplies do I need in the bag for one or two days of hunting?
I'm coming from the function standpoint because I do a lot of hill tromping and hunting with mine.
First priority is whether or not you'll be wearing gloves, which will determine where things are and how you're going to get at them.
After that, I carry a small horn (no more than 20 shots worth of powder, or 1600 grains/ 1/4-pound) loose in my bag.
A pound to a pound and a half of shot translates into more than a dozen shots, and anything more is excess weight. I've got a small shot bag loose in the bag, too.
I find that it's easiest to get to wads and cards with two shallow pockets across the face of the bag just below the mouth. I only put half a dozen in each, with spares in a small leather bag loose in the bottom of the bag.
I'm hunting in serious brown bear country, so I have a loading block with three patched RBs. Shove one down on top of the shot loads and hope for the best on a confrontation.
After that, it's a very small tool kit plus a spare flint if I'm flinting, and spare caps if I'm capping. In the latter case my capper is leather and rides in a pocket on the bag strap.
Dat's it. Total weight less than 3 pounds, and I could certainly cut that in half with less shot and powder. Lord knows I only wish I needed that much on a hunt!
