Hello Jim,
Currently there's not much ways to customize the report. You can only modify the title and description and, via Python, add some custom lines to the final report page using user_settings parameter and by passing to it a list of string tuples.
As for the error units, they are chosen adaptively (cm, mm), if Use Derived Units option is enabled in the General Preferences tab. If you disable this option, the error values in report will be in meters (or in ft, depending on the coordinate system units).