Unspayed dogs have a greater chance of getting breast cancer and uterus problems such as pyometra (infection in the uterus). Because of these problems statistics show that generally spayed dogs live longer than unspayed dogs.
Absolutely not the uterus is what holds the baby in the womb.
yes
No
has there been any known cases of a women getting pregnant without a uterus
No. The tube do not stretch and will break when the embryo grows. The embryo then dies. The mother will die if this is not taken care of.
Yes, a dog would have to push to excrete her puppies from her uterus.
No. A uterus is a home for a baby, containing vital nutrients for it.
Yes, dogs eventually die.
Fetal development goes on without awareness of the shape of the uterus.
Dogs don't 'hatch' ! They are born. They develop within the mother dog's uterus (just as a human baby would inside its mother !).
Well, no. Dogs need to eat just like humans need to eat. Without food they would would die.