Hi,
I think that the various camera positions should be tried. Personally, because of the wide angle lens and it's barrel distortion, I think that a point of reference is very helpful. I.E. to be able to see a part of the vehicle in the camera view is good.
Hopefully on the built in systems in new cars, they will put perspective correction lenses on the camera that straighten the barrel distortion. Other issues like greater "F-stop" range, with more steps would be good too.
On the screen side of things, the biggest issues arise from bright light conditions: they need to be shaded from having direct sunlight on the screen AND in the case of my screens, they go
blank when they overheat. Mine generate a fair bit of heat (from the backlights) and I'm sure that LED backlights would be much better.
I was interested and a bit surprised to see glimpses of video mirrors in the GM Hy-Wire. Look at about 2:18 to 2:27:
To be frank: those video cameras suck! They are nearly fish eye wide angle, and the side view screens are about 1/2 taken up by the side of the car. The quality may be washed out because videotaping a video screen is very hard to do. But obviously GM didn't work very hard on making them useful.