[Zubersoft]

If you use the default storage location, and copy all of the contents of that storage location folder to the other devices, it will duplicate everything and the library should work fine. There will be an error at startup if you copy the xml files, because the path to the folder will be different on each device, but you can then just select the option to use the default storage location. If you copy just the song files/folders and mobilesheets.db, that should work perfectly fine without the previously mentioned error at startup. You wouldn't rely on the sync feature anymore if you do this - you'd just upload/download files, or use a third party file sync application. 

As far as your second question, go to Settings->Library Settings->Song Title Formatting. The format for the caption field must be different on each device. You can choose what fields are displayed for both the title and caption.

As a side note, if you want to share a library backup file and/or the sync folder with me, I'm happy to investigate this more, but without that, I will have no way of providing more information for you on why the sync is failing.

Mike