The flight did come indeed from CHR, and it landed somewhere else in Afghanistan before landing in OAIX. In regards to National they fly heavy crew most of the time I believe. (even if it is a relative short day)
As far as flight time goes...I believe it is more in the 3.5 hr range (depending of wind), since a lot of airlines (especially one being US) can not fly through Iranian airspace. Just my 2 cents.