I don't see any problem with using the bullet to compress the powder. I've loaded thousands of rounds of .44 Mag with BP and RS Pyro with just a beeswax cookie between the powder and bullet. Used to cook up my own lube but it was a PITA and made my seating die a real mess. Eventually went to cast bullets already lubed with SPG, haven't used anything else since. In fact, the avatar to the left is one such load.
Just don't use cast bullets with normal smokeless bullet lube. Took me forever to get the crud out of my Marlin that was about the consistency of concrete. At CAS matches I always kept a plastic jug with soapy water in it to dump the empty cases. Just shake 'em up at the end of the day, rinse 'em and lay the cases so that the water can run out of 'em. Then tumble 'em when they're dry. Your brass will look like hell, but they'll be OK!
Oh, and clean the bore with diluted Windex, works great-- I cleaned 2 revolvers, a Marlin lever action, and a double-barrel shotgun after every match with that for 3 years. The cheap stuff from Walmart works just as well as anything, don't waste your money on commercial blackpowder solvents. Dry the bore with patches and/or a blowdrier, and just use WD-40 on it afterwards. I haven't had a single problem with rust. Ballistol is nice to have if you can find it, but WD40 works just fine for rust prevention(and sure smells a lot better).
Rick