The soft lube is to keep the the residue soft. You can virtually fill the case as much as it'll hold. A drop tube would dump a little more in the same space. I'd just use a Lee powder scoop, myself. That's what I use with my Ruger Old Army cap and ball when I don't wanna mess with the powder flask.
Having played with cap and ball revolvers for 35 years, I'll use smokeless in my .45 Colt, thanks.
BP is fun, fun, though, make no mistake! There are plenty of reasons to do it with a .45 colt beyond even SASS competition. Still, I get my thrills with the ROA and a .31 Remington CVA I have. I'd like to get another Remington, but no cap and ball can come as close as a Ruger Old Army for perfecton. It'll shoot better than a LOT of smokeless cartridge guns and it won't crud up even in 100 firings without cleaning. Accuracy remains at about 1.5" at 25 yards with a 220 grain Lee cast conical. The cylinder has a flange at the front designed to keep fouling out of the cylinder pin area. I had a Colt Navy clone that would crud up around the cylinder pin in about 50 rounds and slowly freeze up requiring cleaning. No matter, easy to pull the barrel off, and it ain't like you can reload it in any semblance of speed. LOL! My old stainless old army, before it got ripped off, was neat. I had a rubber pachmayr on it. I'd come home, pull the cylinder out, stick it in the dish washer, and it got spotless!
I mean, how easy can clean up be????