<p>Look up lucid dreaming and REM sleep. Those two topics will answer most of your questions.</p>
<p>1 & 2) Everyone dreams (although I’m not sure about babies in the womb). Everyone. It’s part of REM. The only reason people don’t think they dream is because they don’t remember their dreams. I, for example, haven’t remembered a dream since before senior year began in August.</p>
<p>3 & 4) Lucid dreaming is when you are aware that you are dreaming. In this situation you have complete control over your dream, including the ability to wake yourself up from it.</p>
<p>5) When in REM (and I believe Stage 4 sleep too), your body is literally paralyzed. This is to prevent your body from acting out what your mind is imagining, which could potentially be dangerous. If you wake up during/just after REM, your body may still be paralyzed, which is why you would experience exactly what your friend did.</p>