As far as the time perception effects, it's standard in the gun world to say things slow time. Research suggests that it doesn't happen but there it is a later memory effect.
Things do look clearer in the center of your focused vision as the systems responsible for fine detail tune up a bit. Thus, reports like Cirillo (IIRC) saying his sights were crystal clear is probably true.
Auditory exclusion is selective attention effect combined with memory. Your hair cells in the cochlea get fired no matter what you perceive.