It seriously depends on precisely when the murder takes place. Second question: the fuck? It depends on a million things. Third question The fuck is wrong with you??

Depends on stage of pregnancy, circumstances of death, how quickly the baby can be removed from the corpse. The biggest factor is the mothers heart is no longer circulating blood, the baby even if it's late in the third trimester may not receive enough oxygen to make it. It's extremely circumstantial, but hypothetically yes a baby could survive.

As for the other 2 questions, those really don't have much to do with the initial question. You may want to just look at the general science behind raising children. I'm sure finding out your mother died and you were born in this way would be extremely traumatic and probably have a massive influence on who you are as a person. But most likely the child would be sheltered from that knowledge until they're an adult, and perhaps forever.

I wonder what prompted this specific question, but if I remember correctly ::: spoiler spoiler Guts from Berserk ::: is born in this way.