I again urge you to try Shauna Kelly's instructions. That gives very solid automatic numbering.

As for customizing the Ribbon, you can do it with XML. I suspect much would be best done in a Windows environment and ported, though. Although I no longer use a Mac, I have it on good authority that such customizations do work in the Mac version 2016.

Customize the Ribbon (It doesn't take rocket science)
That web page was originally written for Word 2007 which had no way to change the ribbon through the user interface within Word. However, the XML methods give you a far superior modification that can be stored in individual templates that can be used as Add-Ins. It isn't easy, but it can be done. The basic book on this is RibbonX: Customizing the Office Ribbon by Robert Martin, Ken Puls, and Teresa Hennig