If you're looking for a reproduction cap & ball revolver, site sponsor: Marstar, is a good place to start. Likewise: Wolverine. The sites feature both Colt and Remington reproductions, in both .36 and 44 caliber, For accessories, sulisa has already offered some good tips. Other sources: Rusty Wood Trading. Track of the Wolf. Dixie Gun Works. Shooters Choice. To name a few.
Brand choice remains a personal one. Uberti makes excellent reproduction revolvers. Also: Pietta. Brand choice will boil down to which one best suits your taste and budget.
One of the best youtube sites to visit: duelist1954, A wealth of information here, on all aspects of cap & ball shooting. Co-incidentally, host Mike Beliveau recently aired a video on choosing accessories for c&b loading and shooting. Well worth a look. Another: Blackie Thomas. Good info here, too. Also: capandball. These three should answer many of your questions. Lots of other sites available, as well.
As already mentioned, you'd be wise to seek out an experienced c&b shooter, to show you the ropes. This discipline isn't difficult to master.....but it does have its share of pitfalls for the unwary. With the popularity of this type of shooting, your local gun club should have several experienced shooters that will offer to mentor you.
Also: be sure to pick the brains of folks on this forum. There are some very knowledgeable bp shooters here, who will gladly assist.