Villette's got it right! Read read read!!
As to temperment, just like humans, each yorkie is an individual. I have always thought temperment is part genetic, part trained. If you are sweet and gentle and you raise a pup to be sweet and gentle, that is what they will be.
SPOIL AWAY!! Yorkies just LOVE to be spoiled!! But again, if you don't want to make a habit, be careful what you do for spoiling, lol!
Good luck, choose your yorkie well, and you will have a friend that you can love on and cherish for many years to come!