Alien in a Prometheus context

For the last few nights I have been rereading Alien to whet my appetite and to try and gleam any nuggets out the original story. A couple of things I spotted. When Ash is discovered to be an Android, he has the following to say about the alien signal. [i]Company specialists already knew that the transmission was a warning and not a distress call. We were to investigate a life form, almost certainty hostile according to what the company experts distilled from the transmission[/i] And also: [i]The derelict spacecraft we found had landed on the planet apparently in the course of normal exploration. Like Kane they encountered one of the alien spore pods. The trans mission did not say if the whether the explorers had time to determine if the spores originated on that particular world or if they had migrated from somewhere else. Before they were all overcome they manged to setup the warning to keep inhabitants of other ships from suffering the same fate. Where they came from they were a noble people. Hopefully man will encounter them again under more pleasant circumstances[/i] Dallas appeared to be mutating into a cocoon (egg), but hanging next to Dallas was Brett in a different cocoon. Different in texture and colour from the first. While Ripley couldn't know (according to the text) but it was the same as the broken urn on the derelict. - interesting that mutating into 2 different things. I know the books are not strictly canon, but when ADF wrote the books he would have been working from the screenplay script the movie was based on rather than his own imagination.