[...] have one LAST question:
I'm a bit sceptical here
I was wondering if I wanted to build a robot with a spinning disk do I want a motor with a lot of torque or hi RPM?
That depends on several factors.
High RPM is good (up to a point) for wreaking carnage, but the faster you want it, the more important the balancing and strong perfect bearings becomes.
The damage you can do with a given shape of disc depends on its speed and weight (inertia).
How fast you get it up to those RPMs (after an attack that slows it down or stops it completely) depends on the torque of the motor.
So, you need to consider how heavy you want the disc. Calculate how much speed is needed to reach a certain inertia (then you know the needed RPM) and then decide how fast you want it to be ready again and calculate the torque needed.
Don't forget Google