You found the answer but in case anyone else has the problem: Connect the EHD's USB cable to any on the 3 ports on the Hopper or a powered/unpowered hub from one of them. Insert the drive's power brick in an outlet. Unpowered drives may work. Accept that you added the drive after it indexes the contents. Press DVR and notice there is a gray button between the red and green ones, labeled with a name you chose. Move to it and select it and the drop-down menu will list your local name and External Device 1 and E D 2, if a second one. (Suggestion: if you are far from the top, then just press red and right twice.) Select one and go from there. You can view or delete shows as needed. You can select Folders by Title/No Folders or select DVR Date/A-Z/Rating/Most Watched for the ordering.
As you found there is in Menu+2 down+3 right an External Hard Drive tile which allows transfers between EHDs and the IHD. This seems so different that the other operation on the EHD.