Real black powder is going to be the hard one to find right now. It is about as tough as finding smokeless powders. Places will have it in stock for short periods of time, but it sells out quickly.
As to loading shells, are you planning on loading in brass (Magtech) hulls or plastic hulls? I have only loaded the brass Magtech hulls. Since the hulls are thin walled, you actually use oversized wads and cards. Loading is very straightforward. Magtech hulls use LPP and not 209 style primers. Prime, load your BP charge, and then an overpowder/Nitro card and compress the card in the hull. You don't want any dead space between the powder and overpowder card. Next add a fiber cushion wad followed by shot and then an overshot card. On the brass hulls, you don't need to crimp them, just glue the overshot card in place.
Among other places, you can find components at Circle Fly Wads and Ballistic Products. Circle Fly has info on their site as to which size wads you will need. Ballistic Products also has a manual you can buy which specifically is for loading black powder in brass hulls.
Once fired plastic hulls for now. I have primers, shot, and Lee hand reloaders for now. Picking up some hulls this week and ordering wads soon. ( Appreciate to sources for those). Need powder and I’ll be in business.
I also picked up an antique roll crimper and the Lee reloading kit has a star crimper…
Thanks!