Layouts repository

Is there an online repository of DIY layouts that users have created and uploaded?  I'm aware of the ones available on the GitHub page, but was wondering if there's a place where I can find more?

What I'm REALLY looking for is the original Garmin layouts for the Edge 840, that I can simply tweak to my needs.  Does such a thing exist?

When I create the data screens/layouts in my Edge 840, are they stored somewhere in particular on the device as an XML file, that I can then customise?

Thanks in advance.