My thoughts. I know I've not gotten ranger far yet, but I'm looking at doing so eventually. (Ammo and has been my main reason for delay.)

#1 doesn't concern me as much. I don't say it's not important, but it's not as big of a limiter as the other two for me.

#2 should be an additional pair of traits... say something like..

Passive Traits:
Moving Shot I: RNG Lvl 40
Ranged Attack is not interrupted when moving at walking speed (Auto-Run turned Off)
Moving Shot II: RNG Lvl 80
Ranged Attack is not interrupted when moving.

Also agree that an auto-attack option needs to be explored for rng. Maybe set it as an option for /ra, such as '/ra on' and '/ra off' for us to use as macros, but tie these to a passive trait given to rangers at lvl 1.
Thus, using /ra on as a war does nothing... Make it a ranger thing.. or maybe even a RNG/COR ability. Help them out too.

Constant Barrage: RNG Lvl 1, COR Lvl 1
Allows Ranged Auto-Attacking (Trait not available unless Ranger or Corsair is Main Job)

#3 could be, as you say, NPCs. I would say that they would sell lvl 60-70 ammo, and barter materials for lvl 70+ ammo. Really would be useful.