Going to all nuke generated steamer carriers was a stupid idea to start with. We needed at least three conventional steamers. Faster crew training in the event of mass casualties by about two thirds, faster to build by half, and cheaper to build. If our politicians had allowed drilling and exploration for our own oil the fuel would have been cheap as well.
Built where? The U.S. has one supplier of carriers, one for large amphibious ships, two for subs, two for destroyers, two for smaller amphibious ships, two for LHAs, and one for oilers and the like. And those yards that do build the ships are at capacity and are incapable of delivering a quality product on time and within budget. Link
There is no functional difference between a nuclear carrier and a conventional carrier. One has a very exotic way of boiling water....