Obviously the more efficient your PT is, the more even your levels, the higher the Mob is, the less arrows *per level* you consume.
You sir, are 100% correct IMO. +10 points to you :).
Sorry I cannot add any info to this thread because I feel it is very difficult to judge arrow useage. Different Rangers use different amounts of arrows.
IMO a Ranger should be firing just enough to not be taking hate all the time. Having the mob run after you every couple fights or so is ok but you shouldn't be taking aggro like a Paladin.
The opposite is true also. If the MOB hasn't even looked at you once for the past hour then you should pick up your rate of fire and lay it on them alittle more.
The 2 stacks an hour rule is probably the most acurrate measure I have seen so far. Arrow prices vary on all of the servers so your gonna have to look at your servers AH and make the estimate yourself.
Personally I don't worry about the price anymore. I make money and I spend it on arrows. I fight as long as I can and once Im out its back to making more gil.