We've got three, but they have a pet door (shared with the dogs) so they just come and go when they need to - we did have a litter box a few years ago and it was just a complete disaster; never again.
Oh heck yes. Our place is about 90% hardwood flooring - I'm glad that all that hair isn't trapped in carpets, but with hardwood floors it all seems to accumulate in certain spots (there's one point under one of our coffee tables which seems to attract a cat-sized ball of hair in a matter of hours :-)
We've never had any in the house - the cats do bring them and other critters to the back step occasionally, though (but the only thing they've ever brought right into the house was a pigeon - boy was that ever a fun thing to find first thing in the morning)
cheers
Jules