Was shorter than the drones and warriors we had seen in the past. I'm not entirely sure how bit it was though the illusion of it being smaller was probably down to it mainly being on all fours for most of the film.
Yes, the description she gave andrews in alien3 was of the aliens she had previously encountered as she was not aware of the visual appearance of the new alien at that point.
you also have to remember the hieght would be different coz of the spinal colum being that of a dog's or an ox's(whichever)if it has a spinal colum...anyway wat ever supports it would have to be different for it to be on all fours anyway