Can you cerakote a bare action? I ordered a new barrel, recoil lug, and nut for my Savage and am having in coated in FDE, can I get my action done without interfering with the barrel threads?

Cerekote adds to dimensions..I had a barrel and gas block cerekoted and after cerekoting the gas block wouldn't go back into position.  I had to use some sandpaper and remove some of the cerekoting on the barrel where the gas block belongs.  

You can cerekote things, but keep in mind that the threads may need to be chased a bit so things will fit like they did before.   Cerekote is a great coating and that is because it was designed to be tough..that toughness also makes it difficult to remove if you need to.

You just plug the threaded portion.