I visited the Rad showroom in San Diego last week while on vacation from RI. Great display of ebike models.  The bike trial ride area is a plus.  While I was there, several customers were taking delivery of bikes, two at a time. 
Congrats
John

How can I get detailed info on how the ECO mode operates on my rad city and what I should see on the display?

I bought the bike in March 2021.   As I ride ( primarily in PAS 2), the mode display shows ECO.  This is good.   Research on the web implies that I should be able to see the power feeding back to the battery from the motor. However, all I see is zeros.   

PS:  this bike rides like a dream.  Went together well out of the box.  Only needed a small adjustment to the derailleur by a bike shop.  Have 250+ miles.
Thanks