The date and time will be unique to when the AutoText was inserted, but not to the document unless you put a document identifier in it. Look also into document variables which can be inserted in your templates. Again, though, modifying them requires vba.

You can expect some problems with your code running. Some users may have their machines set up to reject all macros without notice have no trusted locations.

Does your custom ribbon require code? If so, it may not work on those machines. Consider distributing a separate setup procedure with your template in a zip file with the template.

You can have an icon for a custom AutoText gallery on the QAT with no code. Unfortunately the icon and tooltip are both particularly unhelpful.
See 2003 WordArt Add-In for 2010-2013 for an example of a Macro-free Add-In that uses Building Blocks Custom Gallery 4 to hold AutoText.