Teddy has the same problems - he shakes in the car, is nervous around people and never wants me out of his sight.
Your Bruiser will either grow out of it with constant exposure or he won't. It's probably still too early to tell so I'd keep doing what you're doing ie taking him everywhere with you, making him go in the car (don't bother with treats if he's not receptive - praise and pats are as good as treats) and exposing him to new and different situations.
If he's still doing this in a few months, come back to me and I will tell you exactly what my vet told me or you can read some of it here:
http://www.yorkietalk.com/forums/yor...my-others.html
Take this info I received re: Teddy to you with your vet and see if they agree/disagree/want to elaborate based on your situation etc.
As far as the other things, I'm sorry I can't help! I was fortunate enough to have Teddy potty trained at 14 weeks and he never ate poop!