Here is what to do about your issues:
1. Chewing: Get a spray bottle and fill with distilled white vinegar. When your dog goes to chew something, say "no chew" and spray the object of his interest.
2. Wear your dog. Attach his leash to your belt loop and you will know what he is doing and when.
3. If you can't watch your dog, crate him.
4. If your dog barks when you are not home, read this:
Separation Anxiety and Destructive Dogs
5. If your dog barks excessively at everyone and everything, he does not see you as the pack leader and is confused about his place.
-Revoke furniture priveleges.
-Eat before he does and let him see you eat.
-Mix his food in his bowl with your hands to put your scent on it.
-Make him sit and stay before you let him eat.
-If he goes to bark or starts to bark, say "Ah Ah" in a sharp tone of voice. (Think Victoria Stillwell on "It's Me or the Dog."
-Praise him when he does well. This will enforce the good behavior.
-If your dog barks, whines, jumps or vies for your attention, ignore him. Do not give him attention until he is calm.
Invest in a good behaviorist to come out to your home and work with you on what you want to get fixed. Petsmart teaches basic obedience...it does not teach you how to deal with "problem behaviors." Also, not all trainers are behaviorists and therefore are NOT qualified to work with you and your dog on problem behaviors.
I know you did not intend to put this post up to get slammed, but I was in total shock when I read that you are even considering this type of collar for your yorkshire terrier! If any trainer or behaviorist even suggests this to you, get your money back and find someone qualified!
Walk your dog! Several times a day, if you must! Get a friend/neighbor/family member/professoinal dog walker if you must. Exercise is key to a well behaved dog as well. Some people mistakenly think that a small dog does not need good exercise or mental stimulation from a controlled walk, but they do.
Shock collars should ONLY be used by someone who knows what they are doing with them. The average dog owner does NOT know how to properly use them, therefore abuses it without even knowing it.
PM me if I can be of any more help to you. I wish I lived closer to you (I'm in NC!) because I'd love to help you one on one. However, I have had extensive experience with these issues, and these techniques have worked for my clients.
You do need to take into account that change will not happen overnight. It takes patience and consistency. Your dog needs to see you as the pack leader. Fear is NOT the way to get yourself that status.
Good luck and I hope you put these techniques into play!
Monique (The Dog Nanny in Fayetteville NC)
Owner of Liberty Dog Training