Torque is the cross product of r and F where F is the force and r is the vector from the rotational axis to the point of action. The magnitude of torque can be found by simply multiply F by d, where d is the perpendicular distance from the axis of roation to to the line of action. In the case of props, d is simply the length from the hub to the center of mass of each blade (find the torque of each blade individually then, add them together)
Maybe I should keep silent but strongly feel that the "F" in your formula has nothing to do with prop selection. If you prop an engine to turn 8000 RPM and then change that prop to a larger diameter smaller pitch prop that also loads the engine to 8000 RPM, then you have EXACTLY the same torque. Torque comes from the burning gasses of the engine, not the propeller. Horsepower is obtained by multiplying RPM and torque with a constant. Given the same RPM, you get THE SAME TORQUE. That was the part I am sure of
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Then the one I am not sure of
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As for the weight of the prop, I don't think it changes that much things. If an aircraft needs its engine and prop setup to turn 6000 RPM to torque roll, then the kinetic energy of the prop has nothing to do there since kinetic energy has remain the same when speeds remain the same. Let me explain with an example : a fully loaded truck and an empty truck rolling both at 60 Mph. They both have the same engine and both engines work the same to stay at that 60 Mph. Kinetic energy enters the scene only when the trucks want to turn, accelerate or decelerate. If you try to remove or add kinetic energy, then you have a reaction but if you keep that constant 6000 RPM then kinetic energy does not change.
Those were my feelings since I am not a mechanical engineer but am very interested in this kind of stuff. I hope I do not cause any bad reactions.