And a few more points that haven't been brought up yet (I think):
What does Shaw hope to accomplish by traveling to where the Engineers live? Did she forget that the one that she did meet killed several people almost immediately after coming into contact with them?
How does she even know that she will even survive the trip? Are the pods that the Engineers were using compatible with humans?
How long is David going to last as a disembodied head? Does Shaw have the necessary equipment needed to repair him? Does she know how to repair him?