I shoot a CVA Optima, not the traditions but most of your questions would apply just as well to any type of Inline Muzzle loader
Sight vs Scope is definitely a personal preference. I have tried to shoot with open sights and don't find I have much accuracy beyond 25 yards, so I strictly hunt with a scope. In my opinion a good scope is just as important as a good gun. If you can't see what you're aiming at you don't have a very good chance of hitting it. I shoot a Vortex Diamondback on my Muzzle Loader and a Leupold VX-II on my BLR. Both are fantastic optics.
I've tried the white hots, and triple 7 pellets, and prefer Blackhorn 209 over the pellets. I found the Blackhorn was more consistent and burned cleaner. I picked up a few powder charge tubes (Here's a link) which make it very easy and quick to measure, carry and load the powder. I think I bought mine from Young Guns in Porters Lake. (That's also where the gun, powder and scope came from. Great guy to deal with)
I would use a bore spray to clean instead of soap/water. Thompson Center and Traditions both make good ones, you can pick up a bottle for $10-15. Make sure you put grease on the threads of your breach plug after you clean, otherwise it can be pretty tough to get out after you shoot.
Powerbelt Platinums have worked great for me. Give a few rounds a try to see what works well in your gun.