Welcome young buck, hands down you have been given tons of great info to help you out...after all thats what the good folks on this site do! Now don’t rush into gota hunt with it this late season. After you get the gun and all the other things you need you have to, find what load combo shoots the best then sight gun in. Then you need to shoot,shoot,shoot to get use to the gun and make sure your shooting is accurate. There is a learning curve to flinters unlike a modern gun. Also you need to find your comfort distance...50yrds and under, 40 yrds and under...you need to be accurate so yardage will limit you starting off. Don’t think your going to be shooting up to 100 yards...you owe it to the deer and yourself so i say keep it under 50.
Now i see you have a chance at a T/C fire storm, they are good flinters as i have one in SS as my starter flinter over 18 yrs ago. I never killed a deer with it as i only used it couple times a year in the later season...more of go to cabin, eat great food and drink. I started tinkering with prb’s and then tried some Hornaday 240 Pa conicals. After finding my tightest groups...i settled on 70grn 2F goex bp and the Hornaday Pa conical. With this load and me doing my part... best target of 3shots and all touching. To me and hunting in Pa woods 50yards was about make least where i hunt. The other thing i did was get a different breach plug...the origional is cone shaped so the one i got cone was cut off flat then dished out...looks like a bowl. I also switched to black english flints cause the cut agate flints they come with suck. So if you get the firestorm i hope this helps. Also depends where in Pa you live give Dixons Muzzleloading Shop in Kempton a shot...great place and also Fort Chambers muzzleloader shop, Chambersburg Pa. Good luck.