I think it would be nice to have an opaque frame that became transparent once the show was at that point in the path. This would be good to hide some of the clutter until you wanted the viewer to see what was under the frame. This could also be done if there were multiple layers to the prezi.
you can hide details at first, by making them small, or larger and then zoom out to let your audience see the ‘bigger picture’. Animations like in PowerPoint are not available, sorry.