about the US:
"The duties Marine warrant officers typically fulfill are those that would normally call for the authority of a (unrestricted line) commissioned officer, however, require an additional level of technical proficiency and practical experience that a commissioned officer would not have had the opportunity to achieve."
and
"Though in theory warrant officers are specialists, in contrast to commissioned officers who are generalists, warrant Officers may occupy positions within the military that are normally held by more senior commissioned officers, especially in the Navy where chief warrant officers often fill lieutenant and lieutenant commander billets."
About the salute question
...treating guests respectfully is never a bad idea
and there are various subtleties...eg the (US) sergeant major of the army salutes all commissioned officers, and at the same time, according to the department of the army precedence list, takes (ceremonial) precedence before lieutenant generals. My point being, precedence is derived from his billet here, not rank. He'll still keep saluting every officer, although it's probably rare that he'll report to them. If someone would chose to salute a US CW who has a commission from the US president, while serving in a job that is also done by unrestricted line officers, I can't see how that would be terribly wrong. At the same time, if someone choses not to salute, they probably won't get court-martialed...
it's a pleasure to read all the previous discussions, like
http://www.pprune.org/military-aviat...formation.html