Because Jacob imprinted on Bella and Edward's daughter. And the law of the werewolves is that if one of the werewolves imprint on someone then they can not kill the person that was imprinted on.
No because vampires exist when there are werewolves, and Edward and Bella were destined for each other in that way. If vampires and werewolves did not exist then Bella and Jacob would be made for each other as Edward and the others would not be alive and she would have never have met them and Jacob wouldn't be a werewolf as vampires don't exist so he therefore would not imprint on her.
Imprint Entertainment was created in 1992.
Human Imprint was created in 1995.
Imprint - newspaper - was created in 1977.
Rider - imprint - was created in 1908.
Imprint Records ended in 1997.
Imprint Records was created in 1995.
Villard - imprint - was created in 1983.
Picador - imprint - was created in 1972.
Philosophers' Imprint was created in 2001.
Adelita - imprint - was created in 2006.