I'm not quite sure what you're saying in your first question, because both the Danes and the CC's that I feed get fairly large amounts of food. 2 cups twice a day for the CC's and 3-4 cups twice a day for the Danes.
I've met one CC who was ok around other dogs. Not overly friendly, but not aggressive. The two that I deal with on a regular basis...one basically ignores other dogs, the other wants to eat them. Then it's reversed for people..the dog aggro one loves people and the dog-neutral one will try to eat the people it doesn't know. They make good guard dogs; they have a very deep, resounding bark that carries quite well.
I'm sure that if you get a puppy, the CC will accept any dogs you already have, and possibly with good socialization it will be ok around other dogs when they get older. But it's something I would always keep an extra-sharp eye on.
They also slobber bucket fulls!