My yorkies never have scratched up the couch...but they are all different. The only thing Bevo ever chewed on that he wasnt supposed to were my venetian blinds...I think though, he was just trying to get them out of the way so he could see out the window!!
He learned really quickly though that those were mommys and not to do it again!!!
I have never put mine in a crate...We have a baby that does go into a room at night with his momma, but Im sure as soon as hes big enough, he will graduate to our bed with our other yorkie. I never thought my hubby would allow Bevo to sleep in our bed, but dont kid yourself, he is now just as in love with them as I am. It puts a smile on your face every morning waking up to such a happy little face. Bevo "wiggles" up against my neck (almost like a fish out of water) every morning...his version of puppy hugs!!
They are very much people pets. They need and crave human interaction. If you are truly thinking of getting a yorkie, research alot!! This is not a dog to just leave alone and toss in the backyard!! About running off...I dont know if Bevo would, but I will never unleash him and find out either!! Too risky if you arent in a fenced in area!
Good luck with your decision!