American Warrant Officers are Officers. The Army now considers a W-1 Warrant Officer a Warrant Officer (not a commissioned officer) and upon promotion to CW2 becomes a Commissioned Officer. The difference has to do with authority to command troops, issue Oaths, administer Courtsmartial and other legal issues.
Non-Commissioned Officer (which your Warrants are I assume) do not rate Salutes...only Officers....which include our Warrant and Commsissioned Officers.
In my time....there were three breeds of Cat....Enlisted, Warrant Officer and Commissioned Officer....thus simple and easy. Only the American Army could devise a system where a "Warrant Officer" could be a "Commissioned Officer" and thus complicate the heck out of something so easy and "Traditional".
The change has to do primarily with the down sizing in the Troop Stength authorized by Congress....which sets the numbers of Commissioned Officers the Military can have. As the US Military requires Pilots to be Officers....and in the past the Army was confronted with a crisis....too many Pilot slots and too few Commissioned Officer slots authorized....they went to using the Warrant Officer Rank as a way around that problem. Add later manning cuts and there are too few Commissoned Officers for the command slots and other needs thus the Army took another diversion and made Warrants Commissioned.
Simple ain't it.
Simple answer to your question as to exercising proper Military Courtesy....Your Warrants salute our Warrants....and not the other way around.... re Hand Saluting.
The general rules in my day....
Combat Assault....just that....when you load up Troops and land on the enemy or conduct an airmobile assault, provide gunfire support, or recon for an airmobile assault.
Direct Combat Support....you haul supplies to the troops that did the air assault, haul their wounded and dead, provide gun ship support of troops.
Combat Support....any flight that provides general support to combat operations, moving artillery, troops, supplies, or other operational tasks.
Non-Combat flight....Flights in a combat zone that are not operational in nature...training, maintenance, ferry flights, administrative flights not related to combat operations.
My first "tour" in Vietnam, Twelve Months long, assigned to the Unit in Vietnam, I flew 1100 hours with a 1090 being "combat" hours. We did not count "Missions" but did count "hours". Flight time was Skids up to Skids down....(or in my case Wheels up till Wheels down", rotors running refuel did not count as flight time. Longest day was 18:55....as Crew Rest limitations hinged upon the Tactical Situation.....when the ground troops were in heavy contact....we flew. We did have monthly crew rest limits but even they were negotiable. Average months ran about 90 hours flight time in my unit....with some months pushing 140-150 hours. Throw in slow times, additional officer duties, Unit Officer of the Day, Battalion Officer of the Day, Battalion Officer of the Guard, and time off....and the hours could drop to as low as 50-60 in a month. From June '67 to Dec '70....I accumulated 2200 hours I think it was. That included a full tour in Vietnam, a partial tour in Vietnam (got Medevacced after two and a half months), two Instructor assignments, and a full year of 15 months of training (Basic Infantry, flight school, and a Chinook conversion course, and later a Chinook Instructor Course). I was off flying status for three months during that time recuperating.
There was plenty of flying to be had in those days....much like today as our Lads and Lasses are operating at a very high operational tempo. A recent visit to Hunter Army Airfield in Savannah showed the aircraft there to be well used. Every one we saw had high airframe hours and lots of sand in their nooks and crannies.I was impressed by what I saw there....lots of well trained, well experienced, motivated Soldiers!