The only way to tell if your dog is too small to have puppies is to ask your vet. Your vet will be very honest with you.
There's no such thing as nursing too much! The puppies will eat (nurse) until they are not hungry any more, as any infant will. The mother dog produces the amount of milk that her pups need, as they need it.
No, the puppies will not be dumb but if they are in a bad environment it could be possible. I hope this helped!
yes
With any dog, ages 6 - 7 is about it, for the dog's sake.
Take her to the local vet and they'll take care of the puppies.
Yes, a very high possibility
A dog must be sexually mature to create offspring. If this dog has been neutered, then they will not be able to have puppies. Your dog may however, just be too young to have puppies yet.
Yes but there might be difficulties. The female dog has to be the medium sized dog because if the male is quite a good size bigger than the female then the female's puppies would be too big for her to give birth to, and then she would need a c-section. If the dog doesn't get the c-section, she and her puppies will most likely die.
They are many risks of having puppies too early. Stunted growth, personality disorders, not good mothers, unhealthy puppies ect... You should always wait until a dog is over one year old before breeding.
Yes, check with your vet. Only if the pregnancy is too far advanced it may be risky for the mother. But it is so important as a means to stop more unwanted puppies being born (and their puppies and their puppies...). When a dog is in season she cannot be spayed (too risky), but when she is pregnant yes.
They can be too small to safely have puppies, particularly if the father is larger than the mother, or the litter is large. A cesarean may be necessary, or an emergency spay, to save the mother's life. Always consult your veterinarian for a breeding fitness exam before breeding a dog. If a dog becomes pregnant unexpectantly, the vet can administer a 'mis-mate' shot which is similar to a 'morning after' pill. The vet can also perform an emergency spay before the puppies have time to develop.
She might be too old or have scarring from previous pregnancies.