Check out muzzleloading forum.com
Revolvers are fun (not technically muzzleloaders - they load at the cylinder face) and not a bad introduction to getting used to powder, ball & then prime.
I'm a fan of sidelock rifles, especially flintlocks, but they can be tricky and it is likely best to start with a percussion rifle. A cheap percussion rifle works fine, but a cheap flintlock can be nothing but misery. You definatly need blackpowder and not substitutes for flintlocks. It's a shame T/C stopped producing the New Englander. I have both the rifle and shotgun versions and they are delights to hunt with. Light and very handy.
Back before this area opened up to centerfire rifle for deer I hunted during regular season with my .50 New Englander for years. Lighter to carry than my slug shotgun and just as effective. One good shot.