The cream separators range from 1400 rpm to 8000 rpm depending on model. The Tesla Turbine is normally designed for high rpm, but would likely have to run on 50 - 100 psi air pressure to attain those speeds. The magnetic coupler would be supported by a stationary shaft like a CD spindle as seen in this movie:
http://www.youtube.com/watch?v=WFMqPWSpmTY

Then the centrifuge could be on it's own support system so it would not rest on the turbine.

I suggest you could consider this idea:
The Tesla Turbine already has a separator designed right in. The centrifugal forces inside the turbine will only allow lighter material to go to the central exit. 

For example, I did an experiment using both air and water pressures in the turbine at the same time. The water tends to spin around the rim of the turbine case, and refuses to move to the middle until the case gets filled more with water.

Sometimes in a steam-driven Tesla Turbine, drain holes are drilled to allow excess water to drain out the rim. Otherwise, the water will cause extra drag on the discs, and some loss of power. 

So, what you could do is run the turbine at high speeds, powered by milk! Udder pressure, of course! (hehe) It might require 50-100 psi fluid pressure to get the rpms over 1000 - 2000 rpm. 

Yes, there are a couple of Hard-Drive Tesla Turbine Instructables. Perhaps the magnets could be incorporated into a design.

Yes, the CD Turbine can generate power in many ways. Here are some ways I have found...

http://www.youtube.com/watch?v=9DOzgSOFh_4
http://www.youtube.com/watch?v=fogl6cFiOhE
http://www.youtube.com/watch?v=rczWjuwZVFA