There were possibly hundreds (if not more than that) of humans/possible hosts on the ship, as you observed through some scene of how huge the ship was. They were probably all gathered up by the thoughts of the Queen.
As for the Alien carrying Ripley, I don't know what was up with that. It
would be more Alien-like to drag her by the tail, but then again, she was a 'guest' of some sort. I think it was for dramatic effect.
I am a Machina-Alien! (Mok-In-Uhh)"To me, everyone is crazy. The ones in the mental house just got caught."