My thoughts as an archer who has fired both 'standard' and decidedly 'non-standard' ammunition from the same bow:2) A range reduction makes perfect sense. Larger, heavier, less aerodynamic ammunition flies slower (and therefore shorter distances with the same accuracy) than lighter, more aerodynamic ammunition.
On the second point, I kinda disagree. There's not much granularity between range bands, and Short Range caps out at several meters. I'd say keep the special arrows as Medium range, since as you noted the delivery system is the same. At most, maybe apply the Inaccurate quality to reflect that these arrows aren't quite as precise as a standard arrow.