I use pack and go as a way to clean out a folder of the parts that aren't used anymore.  I was going to rename a part as well, but noticed in the nested view the part  was listed multiple times if it was used more than once so I'm guessing that isn't the place to rename files.  I noticed the nested vs flat and didn't understand what the difference was.  Does that make it only show one instance of every file?  Could I use the flat view and then rename files while doing the pack and go?