Monsters vs. Aliens/Fridge


 * There's a lot of people who wonder why  bothered to put Susan in a different outfit before   Keep in mind that the outfit   with her, which the one she was in before wouldn't have done. And seeing as he already expressed disgust with her form and the clothes she was wearing before wouldn't fit her anymore, he probably wanted to spare his own sight and mind from the sight. As to answer the how, he probably had something else change her outfit.
 * The ship's computer, by way of a dozen robot arms of course. It even sounds female.
 * How did the people at the facility manage to undress Susan and re-dress her while she was unconscious? Changing an unconscious person's clothes is difficult at best, and when the person in question is that big, it would be a truly, well, enormous challenge.