Dave, by all means, yes, re-do the insulation in both the crawl and attic if the kraft is not against the finished space.
As to the barrier on the floor of the crawl, I would do this if your crawl stays dry. It's important to your foundation that the soil under a crawl not be allowed to become so arid that it has huge cracks in it; this can contribute to foundations cracking and shifting.
A simple cover of plastic sheeting will help that soil retain some moisture, and is beneficial in a crawl that does not have excess water problems. It doesn't need to be taped and sealed, just overlap joints about a foot, and around the walls cut it flush to the wall, where it lays over top of any exposed footing you may have.