theprequelsrule said:

I surmised a lot of this from the trailer as well. As you said, it is probably not 100% accuate, but I think it gets a lot right. I agree with you in that it is probably a different planet and the alien ship is not the same vessel as in Alien - which had been on LV-426 an incredibly long time (the space jockey was fossilized). Unless some horrible time travel element is in the plot...

I wouldn't be so sure about that last bit. It's been stated, I believe by Scott himself, that "The Space Jockey" in Alien is just a space suit, not an actual fossilized body.