In relation to the Kage discussion, I believe the word kage (ex: in hokage and kazekage) is not used by its direct translation which is indeed "shadow." I believe they use kage in the sense to describe the ninjas as being the best or the most "shadow-like" (as it is widely accepted that ninjas are to be stealthy and have qualities like that of a shadow). So, the direct translation would not really fit because of its awkwardness and that's why it should be kept in its japanese form (and just explain what it takes to be a kage).