Alien Ship - question

1. If the ship gets blown/ damaged in Prometheus then how come the ship is snugly sitting in ALIEN and Dallas & the team enter it? 2. If the ship is blown off like we see it rolling after Shaw and she's running ahead of it how come the eggs survive? 3. Isn't the impact big enough in Prometheus for something to get destroyed inside? [img]http://application.denofgeek.com/images/m/75spaceships/main/derelict.jpg[/img]