Hi havent tried this out yet but is there a way to:
Have a follower that's basically a mule for legendaries? as in - solely follow the leader and not attack? And occasionally pick up legendaries if they drop?
Yes, just set your follower's DB Trinity plugin to only loot Legendaries.
Use the Powerleveling profile that comes with the SimpleFollow plugin for your follower, and you're all set.
Although I'm curious as to why you wouldn't want the extra free DPS.