#2 is a little vague as well. While I think everyone would agree that people who do a drive by shooting should be prohibited, does "crime of violence" include a guy in a bar fight? Currently federal rules include domestic battery. These are probably tougher places to draw the line, but that doesn't mean you can't draw it.
"For the benefit and enjoyment of the people" -- Inscription, Roosevelt Arch, Northern Gate, Yellowstone, near Gardiner, MT