Okay… I figured it out. At least the part about how to get any report to become a “Prepared Report”
It didn’t matter how hard I tried, I could not get the instructions in the official documentation to work.
Until I read this post:
.
When you go to that post and start scrolling across to read the first line of the error, you come to:
'user' : 'Administrator'
It was one of those forehead slapping kind of moments. The official instructions do not make any mention of it, but in order to get the setting to actually work you must be logged in as Administrator before you go to the “Role Permissions for Page and Report” to set the flag for Prepared Reports.
If you go to “Role Permissions for Page and Report” as a regular user, and then set the flag for Prepared Report the setting will appear to be done, but it doesn’t actually work. It only works if you do it as the Administrator.
Once set by the Administrator user it becomes a Prepared Report type for all other users.
It would have been nice to have this little detail 2 days ago 
At least I can present the answer here for anyone else that stumbles on this task.
The pat that was so infuriating was the “Official Instructions” that I linked to in the first post, included a GIF example of how to set the flag. Even in the official GIF explaining how to do it, the logged in user is NOT the Administrator. Yet, anything other than the Administrator user doesn’t work. 
BKM