1:48 is a compromise twist meant to "do all". The end result is usually acceptable accuracy with a range of projectiles, but rarely "tack driver" capability with any projectile.
I have a TC Renegade with a 48 twist. Many TC's do.
I've killed deer with it with round balls and sabots. It shot both about the same....nothing to go bragging on, but it'll kill deer. I got my longest flintlock kill to date with that rifle-- 90 paces, offhand.
Usually with the shorter guns like that, 70-90gr of 3F is the sweet spot. You can try 2F, but the shorter guns do better with 3F.
As mauser said, sights are all preference. Use what you got for now, and if you don't like it, have 'em changed. It's a little bit of a ride, but you could take it to Dixon's in Kempton for that work. Everyone has their favorite types of sights, so don't let anyone tell you that you need one or the other. Figure out what your eyes like.
You will get very good service from your flintlock with some attention to proper care and use. It's not rocket science, but it does have a little bit of a learning curve. And you will learn some lessons the hard way. That's the process. Ask any flintlock hunter for some of his stories, and I guarantee you'll hear some that cause chuckles now, but caused some serious cussing at the time!
Another option, too, is a maxiball, which will likely shoot fairly well in that rifle.