Flettner Rotors Data

I'll point you in the right direction...

For the rotor rpm (angular velocity) question... look up "Magnus Effect" (the force is proportional to the cross product of the angular velocity and the velocity vector) So your intuition is correct.

As for the larger diameter rotor, you'll want to apply an engineering principle called similitude. This will help you predict how the larger object will perform based on the model's performance. Wikipedia gives adequate information for your application!

Very roughly, the rotation of the Magnus cylinder is the equivalent of camber in a conventional airfoil - it bends the incoming flow, producing the reaction called lift or thrust depending on how it's used. Increasing rpm will increase lift up to a point, but no further; increasing rotation speed beyond the point of maximum flow bending just wastes power. Getting a larger-diameter cylinder does get you more lift - the larger diameter is the rough equivalent of increased chord in an airfoil.

The other answers are good. You might also want to Google for the use of Flettner rotors in sailboats. As you may know, they generally provide very high lift coefficients, but also very high drag coefficients.