As in many other things, there are individual differences here.
some babies are born more developed then others and develop at different stages
No, not all babies resemble their fathers when they are born. While some babies may share physical traits with their fathers, others may take after their mothers or have a unique combination of both parents' features.
Inches are on some and millimeters are on others.
Their sizes differ greatly due to many factors. Premature and/or multiple birth babies have been delivered successfully weighing only a few ounces and only a few inches long. Full term babies typically weigh in from 3 or 4 pounds to 9 or 10 pounds and anywhere from 12 to 24 inches long. Some babies are downright huge, born at more than 20 pounds!
No, not all babies have blue eyes when they are born. Some babies are born with very dark eyes.
The hearts of the babies are not properly developed.
Some babies will, some won't. Some babies die of neglection or things like that, others die of health problems. Some even die for an unknown reason (SIDS) while still a few weeks old or less. Many babies born into the world are going to stay alive, but some won't - unfortunately, sometimes we have to just watch them die AFTER actually getting born into the world...which seems worse to me than dying before birth.
Some do...
some babies are born head first, and others are born bottom first. the baby turns, and when the doctors deliver him/her, he tells the mammy (thats screaming in pain) your baby is "breached".
No, human babies can even hear some sounds in the womb.
Yes, but some have to be born by c-section.
That depends upon the species of snake. Some of the smaller species produce babies that are only a few inches long while some of the larger species, such as pythons, may produce babies approaching 20 inches in length.