Perhaps I should say ‘center of rotation’ ALONG 0 of one of axes. Example: base of your MRF cylinder can be at Z 0 m, top of cylinder at Z 2.0 m (if rotation axe is ‘Z’). You can, but do not need to align ‘geometric center’ of MRF zone to 0,0,0.
For ‘load’, try to go with ‘parabolic’ curve, which is good enough to not break you virtual setup.