Yes. You can actually prevent a villager from moving if you suspect someone will be in boxes because you haven't had a mover in a while or if you haven't played in a while you can load a new character and see who's gone/in boxes and then change your DS clock back to the date you last played and stop them from moving. So long as you don't load your mayor it's not permanent.
You mean your new character steps off the train and you want to go into a house to see if anyone's in boxes? Yes, I've done it. I wasn't sure when Erik's move-out date was, so I kept checking each day with a new character until he was in boxes.