CWS is qute simple... you twiddle the knobs on the autopilot and the aeroplane responds appropriately... the 'knobs' in this case are at the end of your arms and legs!
Turb Mode drops the autopilot from CMD to CWS, thus reducing the 'gain' and stops the autopilot chasing the Alt Hold, thus maintaining attitude in turbulence. I can't imagine a CWS system being fitted to a PA28... why would you?