[dafischer]

The cat shouldn't damage the flooring. With respect to the couch and chairs, get a scratching post, and encourage the cat to use it, by discouraging scratching elsewhere.

The best negative reinforcement is a plant mister/spray bottle, with the nozzle set to jet stream. Only use it when you catch them in the act. It will keep them away from the upholstery, and give them some exercise, as they run like hell when squirted.

Another method I've heard is to hang inflated balloons over the arm rests, above where they'd scratch. One claw in a balloon will also give them some exercise.

And by all means adopt from a shelter, as you'll save a life, and they'll love you for it. I think you'll find that they're great companions, and very self sufficient, read no walking or cleaning up after.

YMMV. Good luck!