Using PVC trim as a skirt around brick pillar foundation

It appears my crawlspace was enclosed with plywood that did not withstand the weather. I need to remove approx 2 feet down of rotted wood and i wanted to reframe it with ground contact pressure treated wood & then white PVC board. I have someone willing to assist me with the job & i just had the following questions Should the PVC board go across the brick piers or just frame the area in between? Does that matter? What should be used to finish off the ends of the PVC to prevent water from seeping? Does the PVC sit on the dirt too next to the wood or does it sit above? This is an unconditioned crawlspace. Is it okay if i insulate behind the boards being replaced in addition to under the floor joists ? I plan to put a caper barrier down next year