As someone whose experienced it, I might be unique but I have a few discrepancies.

Interestingly enough I've never had the feeling I couldn't control my breathing- I've actually successfully woken up my wife by intentionally breathing extra fast and hard- but I can't talk. My hunch is that the breathing control is definitely a different mechanism than the paralytic.

The hallucinations are a definite, but it's more like lucid dreaming. Usually I've speculated something might happen, then it happens. Mine was usually a hobo that would run into my room and start stabbing me. I'm used to relatively scary dreams so they didn't disturb me much, and by the last time I was well aware of what was going on and I basically just rolled my eyes at the stupid games my mind was playing. The "paralysis" was completely distinct from the hallucination, though.