1). Try it, and see what happens. You'll never know unless you try it. It should be safe, as long as you use blackpowder or proper modern substitute. Don't use smokeless powders.
2). I don't think it will work. A 1-66" twist is designed for round balls I think you will keyhole the bullet-BUT, if you don't try, you won't know.
3) You don't have to paper patch the bullet. You can just lube it, with something like Bore Butter. Maybe even Lee liquid alox lube may do. But again, go ahead and try it. I think it would be tough to load without a false muzzle. The old Civil War era benchrest guns used a paper cross patch (Chase patch), and were accurate-but, they also used a tapered false muzzle.
4) Personally, I'd stick to the good ol' round ball and a small amount of 3F black powder, and go squirrel hunting, as it was intended to be used.
Good luck. Be safe (use pure lead, not wheel weights. It will be easier to load/engrave with rifling.)
