Ditto what others said about training cats to use a scratching post. Some other thoughts/tricks:

- If they do scratch where they should not, put strips of scotch tape in that spot, they don't like that and won't scratch there again;

- When you catch them in the wrong spot, gently carry them over to the designated scratching post/spot and simulate with their two front legs the act of scratching;

- Keep front nails trimmed!

On the litter, our days of smelly litter ended years ago when we switched to bedding "litter" like that used for gerbils, rabbits.... Currently, we are using aspen shavings which absorb better than the pine or cedar. It is also much nicer not having to step on the little stray litter pebbles that make their way around the house.