As far as the walking goes I would walk Chester as much as he could take and that ensured he slept straight through the night! Pups have a TON of energy and plenty of exercise is the best thing for their muscle tone and heart health. Huey not being as playful right after his walk is just a sign that he got plenty of exercise and simply doesn't have as much excess energy to burn...which is a good thing in the evenings!
As for the collar, pups will scratch at a collar for a week or two until they get used to it. Just put it on Huey and don't take it off and he will adjust in short measure. If you take it on and off constantly he won't get used to it. Chester scratched at his collar for a good two weeks and he scratched it up pretty bad with his nails, so I suggest you get inexpensive ones until he gets used to them and then you can splurge on fancy ones!
Good luck! Everything will be fine...I promise!
"My little dog: A heartbeat at my feet."