I can only answer part of your question. I've never used ash with CP
although the premise of ash fertilizing the fire area makes sense.
There is a natural succession that takes place in eastern North Carolina
when fire is removed from the picture. Basically the forest moves from
fairly open pine trees to deciduous (often oak) trees creating dense
shade. This dense shade will chahge the types of plants growing at
ground (CP) level. However, the decid. trees are very sensitive to
fire and periodic burns keep the forest as open pine. The Nature
Conservancy recently identified some impressive stands of CP on the Fort
Bragg, NC military bases. Apparently artillery shells on the firing
range started fires on a regular basis and the CP thrived.
Jeff in NC