We have prepared a PDF tutorial in how to ‘Relocate’ a building in Revit. It has been through three draft versions, with testing by us and some users. Time to release!
It has been prepared by ArcMonkey2 (Kaylene). She is rather good at these things.
It shows you how to keep the existing building plus the moved version within the one project file, and still be able to edit either version so the other matches.