Well, if you don't mind- I'll answer a bit.
Pulling over a vehicle merely to check on the liense is not alllowed. (darn stupid too) However, running the plate/owner for a current license without stopping it is allowed. if the license check comes up bad, you can stop the car.
Roadblocks, as you refer to them, are a different matter. You do not need a reason to pull someone over at a roadblock. A "license check" roadblock sounds real stupid also.
Aviator- actually, I misunderstood your intentions, no flames intended. I thought you were another troll like some on this board, but you appear not to be one, you are a concerned citizen. But btw- as I said in my post-the right to reamin silent is available any time. Should you use it always-of course not if you can be quickly cleared so the police can go back to finding the violator.
The questionnare itself still only applies to Federal agents.
However- your target is wrong. Don't bust the cops as they are doing their legal duty. Call up the mayor, the chief, etc and tell them how the resources could be better used. Get people together on that and results may happen.