I would think the most important thing KPI does for a suspension's performance is the jacking effect.
I'm not sure about that. When you turn the front wheel, both of them have this effect so it isn't just the outside wheel. Once the car is cornering, I don't think their is enough jacking to make a difference. It seems like it would be a small percentage of the body roll, so a much smaller effect then an anti-roll bar for example.
exactly counteract the camber loss from body roll. In the real world this doesn't happen, and without a system that can actively adjust camber it can never happen (think about steering angle vs. g-force at different speeds and you'll see why),
There are compromises and what one hand giveth the other takes away. I think the good example is braking verses cornering. It is possible to do what you mention in the case above, you could easily over correct. So that as you corner the front wheel would go from too little camber to too much (negative). For instance if you used a really short upper wishbone. That will really hurt straight line braking though.