Mark,
Not being a hw expert, when you saw right or left, how do I know - what orientation is the socket in?
My leafdd connected such that the cable went backward (towards driver) in the car, my OBD extension (which I mistakenly took a photo of for you) went forward (away from driver). Close call, but I probably prefer the former.
As to EV vs CAR bus I'd definately find one useful to experiment. I think the Jury is still out - more exploration needed, though it's easier to pick much of the data from the EV CAN bus especially during charging (useful to monitor) but not all......