I am not a fan of the smaller flintlock offered by Cabela's, as the barrels are pretty short to be calling it a "longrifle", and the locks are small (imho). But as they are on sale for $130 - $150 less than what I'd recommend, I can't tell you it's a bad idea. (
Unless you are looking for something acceptable in a historic venue, then it is a waste of money. imho) I'm sorry, you didn't ask about any of that, so...,
Your owner's manual will tell you what you need, but I'd try a .490 ball, and a .010-.015 patch from cotton ticking. Go to Wally World or any other reasonably priced fabric store, and buy a yard of ticking material. Wash it in hot water in a machine, then tumble dry. That should work fine. Saliva is a free and very good lube for the patches as you learn your rifle.
I'd say 1/2" ENGLISH flints. Cut flints and the French stuff never seemed to work well for me. Again, your manual will tell you what size should work.
Start with 50 grains of powder, real powder, not the "substitute" stuff. Shoot it a few times, then find the patches and inspect them. The Cabela's long rifle and Blue Ridge Hunter are Pedersoli products with a rep for cutting patches, and if yours cuts patches you'll need to fix that or you won't get good accuracy. It's an easy, do-it-yourself fix. Don't worry about it for now. Shoot it and see what happens.
Conicals I have found are a lot of mass that in many cases is unnecessary. Conicals were invented to give soldiers faster reload times, not because the patched round ball didn't work very well. Large, dangerous game is another matter, but...,
Your .490 ball will be fine on Mulies and Whitetails out to 100 yards, though you will need to increase your powder load to about 70-80 grains. (Yes..., 100 yards broadside with a heart/lung aim point you should expect a through and through shot from a patched .490 ball in a .50 or .530 round ball from a .54 with an 80 grain charge.) Some folks are going to chime in and say neither are worth a darn past 50 yards, but the actual results shows that as incorrect.
I use 3Fg for both main charge and prime, and I use a .54. Your pan will be smaller than mine, so you may find 4Fg works, BUT it tends to gather moisture faster than the 3Fg when in the pan. Well work out your best load on the range, and IF you decide to go for a deer, then write back for additional tips. No good getting it all now. Get her going good from the bench, then learn the rest.
LD