My dog's poops are small. Is this normal?
Yes, it's completely normal. Raw-fed dogs tend to produce less poop than kibble-fed dogs because more of what they eat gets used by the body. A lot of kibble, especially the cheaper ones, contain a lot of ingredients that the body doesn't need so gets passed out as poop.
Should I be concerned that my dog isn't drinking as much now I've switched him to a raw diet?
It's not unusual for dogs to drink less water on a raw diet because their diet contains quite a bit of water. The important thing to to check their urination and make sure he's still peeing the same amount as before. If urination has decreased or you have any concerns, please consult your veterinarian.