I have one of those as well. Yours looks like an older one. The barrel should say the twist rate in the info, it will be written as either 1:66 or 1:48
If it doesn't say at all it's likely 1:66. If it is 1:66 it will theoretically shoot patched round balls more accurately/consistently, but you won't be able to shoot maxi-bullets or conicals in it and be able to hit anything. The 1:48 twist is a compromise, it will stabilize patched round balls and conicals.
As far as powder-- do yourself a favor and do NOT use black powder substitutes. Pyrodex weakens with time, is hard to ignite and on top of of being hydroscopic (attract moisture/cause rust) like black powder fouling the pyrodex fouling will actually chemically react with/pit the steel under the right conditions, weather it's oiled or not. Hogdon 777 is the best I've found if you have to use a substitute but again it is harder to ignite than black.
Do not use petroleum based cleaners/lubes inside the bore. They'll react with the black and cause hard fouling, gummy residue and constant misfires.
when you clean, remove the barrel and unscrew the nipple from the bolster, and the plug screw in the bolster -- put BOILING soapy water in a bucket, place the barrel breach end in the water and run your cleaning jag/bore mop up and down-- it will suck the water up like a pump and when you push it back you';; see black crud come out the breach. Make sure you get the whole bore. Don't let the water get cold- you want it to evaporate off and not stay damp or flash rust.
There's more to it but look up some of the muzzleloading sites there's tons of info.
Just be careful, you may end up bullet casting and buying all the equipment for that. It's a sickness and it's contagious.