Congrats! He sounds cuuute! Have you taken him to your vet yet? Try taking him just for a check-up.. its good to get your dog introduced to your vet and he probably needs flea/tick and heartworm meds anyway. Call and ask the vet about the BM problem... >_< hopefully it isn't a blockage from all of the stuffies he's been tearing up. More than 2 days without a BM is serious!! Try giving him a few tablespoons of canned pumpkin for constipation.

About the food, what are you feeding him? If its lower quality than what he was getting at the shelter (which probably wasn't great), he might just be holding out for better kibble. When you feed him, only leave the bowl down for 10 minutes, then pick it up until later in the day. Dogs won't starve themselves unless they're sick. Also consider another brand of kibble if he continues to dislike it.. theres sooo many dog foods out there! I definitely recommend buying quality foods from feed and pet stores, not the grocery store

Kongs are good... stuff it with large biscuits, peanut butter around the inside, and even try freezing kibble with water and bits of meat. http://www.kongcompany.com has good Kong recipes! Try bouncing it for him, most dogs like to chase Kongs because they bounce irradically. I'm bad with names... but I like the names Bailey, Hugo, or Jax for Labbies.