RE: Deer Gun Selection help>>>
If you want to get a rifle take a look at something in 30-06 ( I personally like Savage).
The muzzleloader does not give you any real advantages at the ranges you said you would be shooting so the only reason I would get that is to extend your season. So if that is your goal then go for it.
If you want to get a shotgun take a look at an Ithaca 37. You should be able to easily get 3" groups at 100 yards with their old smoothbore "slug" barrel, and you can always get another barrel with interchangeable chokes for it.