Free: Contests & Raffles.
I've had my pup out in some pretty cold conditions, and at the first sign of discomfort, we pack it up. I've also made it a habit to pack a thermometer so I can check his core temp to make sure things are all right in both the heat and cold. There is nothing worth risking the life of your "best friend" hunting partner.
Depends on the breed. My lab stands up to the cold real well- she's 93 pounds of bruteness.