As was said already the PRB is not your only option, but they are usually very accurate out of the TC Hawken.

I assume by where you live you're hunting whitetails? The PRB will be good out to 100yds safely if it's a .50 cal. A .54 cal another 25 yds or so.

The heavy conicals will have more energy, but the recoil is higher, and i've never found them to be as accurate as a PRB.

You can use all the BP substitutes, and of course real black powder. (my favorite). You don't seem to like Pyrodex, but it's a good consistent powder for sidelocks like yours. I would use the Pyrodex P if you plan to use it. It has a little more power than the Pyrodex RS, and seems to ignite easier. After you pour the powder down the barrel.........lean it in the direction of the hammer/cap, and give the barrel a few taps. It will help get the powder in the breech channel. Make sure the hammer is at half cock when you do this so the air will push out. Do this no matter what powder you use.

Try 80 gr of Pyro P with a PRB to start. Add 5gr at a time until you lose accuracy. Then go back 5gr. That will be your hunting load. Don't go over 110gr. Remington #11 caps work the best for me.