Is the puppy a male or female ?
If Chewie doesn't bark and the puppy is a barker, it's likely Chewie will bark too. He may also pick up bad pee pee habits while you're potty training the 2nd puppy. I'm not sure if adding a puppy will change Chewie's personality, but he will probably become jealous, I think that's natural. Seems to me if Chewie is well socialized and has a good temperament the transition will be easier.
I wouldn't leave them alone together until I was sure they had bonded. The advice to make sure Chewie feel like he comes first is good advice.
As for your last question, I believe that most dogs, and Yorkies in particular, are ALWAYS gonna want human contact. I think having two dogs is a wonderful thing, just make sure you introduce the second dog carefully, because Chewie has probably grown accustomed to being your one and only. But if you do it right, then you will find that you get TWICE as much love when you wake up in the morning or when you come home !!!
