I have a vested interest in all three issues. I'm a cat lover, my wife and I have 6. 4 that stay outside as barn cats, and 2 that live in the house with us. How I handle them is like this. Squirt them with water whenever you see them on the car. It's how you train them to stay off counters, etc, works great.
As a paintball player, if I ever see someone misuse a paintball MARKER (gun attracts the redneck idiots!), I rip them a new one. The laws are already iffy on them, and most people look at us as a wanna be militia member, so do the right thing, do not use it for shooting at a animal, or in fact do not use it unless testing at a paper/plastic/wood target, and only on the field.
And then as a car guy if I do catch the cats on the car, they get the water treatment as well as a smack on the butt (like a dog or a kid)! They learn quickly when it happens. And when I park my car to go on tour, it goes in the garage with a car cover on it.