Because the puppies get cold.
Dogs may sit on their puppies to assert their dominance over them. This would be done if a mother dog is disciplining her puppies as well. If a dog sits on a person, it may be cute, but they are trying to assert dominance over that person.
the number of puppies a dog will have depends on the breed, and size of mother dog in question.
The mother might die unless the puppies are surgically removed.
the other puppies will be born and the dead puppy will simply just come out.
You see the puppies around the mother.
Yes, although you should carefully watch to make sure the puppies aren't being smothered or crushed. The mother will lay over her puppies when they are newborn to keep them warm.
It depends on the breed
When they have been weaned, meaning, no longer suckling for the mother's breasts for food. 8 weeks - no less.
No, the puppies will open their eyes on their own in 7-10 days.
It is not recommended for the mother dog to nurse her other puppies after consuming a dead puppy. This can lead to health risks for the remaining puppies, such as infection or toxicity. It is best to consult a veterinarian for guidance in this situation.
Mostly by smell.
Puppies are carried in the middle abdomen of a female dog. After the puppies are born, the mother will move the puppies by carrying them by their necks.