Anyone offer a good starting load (it's 44 cal / 451 diameter balls)? What brand and type of powder do you recommend - any special requirements in a revolver powder? What about those bp pellets?
1. .451 balls should work ok. There are two issues regarding size of the ball: sealing the chamber from hot gas, thus preventing chain fires, and engaging the barrel rifling to create an efficient gas check and stabilize the round. You should get a good solid ring of lead on loading the ball into the chamber to handle the first issue; if you don't get one, move up to .454 balls.
The only way to be sure about the second issue is to slug the bore (force an oversize ball through the bore and measure the impressions left by the lands and grooves with a caliper). This, however, is an advanced project for those who are trying for high accuracy.
Your brass frame requires using mild loads; I'd start with 15 grains by volume and then try 20 grains and 22 grains. You can occasionally shoot 25 grains but don't make a practice of it as over time it will result in frame damage.
I'd recommend using a lubed felt wad (aka Wonder Wad) between the ball and the powder; it is insurance against a chain fire and also lubes the bore to soften fouling and make subsequent shots more accurate and cleaning easier. Some folks prefer to use a grease (e.g. Crisco) over the ball instead; it will work as well but I think it's messier.
2. Goex, fffg. Pyrodex P is the second choice. 777 fffg is acceptable but should be avoided until more experience is gained as it is sensitive to compression and requires care in loading. You can use ffg or Pyrodex RS, but fffg/P are preferred.
3. Pellets are not recommended as they are tricky to handle (they do not like to be touched by bare hands) and tend to break up on loading. They are also slightly more difficult to ignite. Finally, they do not allow the flexibility in loading in that you can only load in 30 grain increments.