Can I assume that the falloff depth is the radius of the brush (a spherical influence) give or take? Also if I try adjusting the brush placement to shallower when using the move brush it flakes out and makes the ear pop unpredictably.
afaik brushes are spherical. Falloff, i.e. distance between inner and outer ring can he adjusted with Focal Shift (o).
For more control look at the options in Brush:Depth. Adjust the imbed amount so the influence is more or less into the surface, or enable Depth Mask and adjust the depth mask above and below independently.
To move the ear without the surrounding head use Move Topological, or activate Brush:Automasking:Topological so that brush influence is masked by distance from the point of brush contact. Sliders let you fine tune that further. Topological works for most brushes, if not all.
Another option to prevent pars from moving that you want fixed is to mask them, or give regions unique polygroups and adjust the Brush:Automasking:Mask by Polygroups slider to 1. Brush will only affect the polygroup first contacted by the pen. Works for all brushes.