With regard to the question about the rifle being easier to snap shoot - it depends on the sights (not to mention training).
A reflex sight, such as my EoTech, eliminates parallax. If you can see the dot, and the dot is on the target, you should be able to hit the target. Your eye doesn't have to be perfectly aligned, just close enough to aligned that you can see the dot.
Additionally, the reflex sight allows the shooter to focus on the target; the dot almost appears as an afterthought.
Such a system is VERY fast, if the shooter practices.
Did you ever wonder why SWAT, ESU, etc use AR or SMG platforms as primary, with pistols in a backup role, even indoors? (Even when they do not plan to use full auto.)
With the right sights, the long guns are faster.