Hi and welcome to YT
. Yes, $600 is actually really inexpensive for a yorkie pup.
As far as shampoo, not all yorkies have sensitive skin...so I'd just start out with a standard dog shampoo, non-oatmeal based. Yorkie Splash and Shine is supposed to be really nice.
For walking, I just took it slow...ie got my pups used to their collars, then used to the leash, then tried walking for a while...if they didn't want to walk, I'd carry them. Eventually, it just seemed to click with them.
Btw, what happened to your 1st yorkie?