RE 1: I'd guess you were experiencing both sleep paralysis and HI. When we are in REM sleep, our bodies always enter sleep paralysis. In the case when you are asleep, it's called "hypotonia". If the feeling of paralysis remains after you wake up, then it's called sleep paralysis. Sleep paralysis can happen before or after sleep. HI can also happen both before or after sleep. If it happens as you wake up, it's called "hypnopompic" instead of "hypnogogic" but it's mostly the same thing. If you google those terms, you can find more detailed descriptions on wikipedia.

RE 2: I'm not so sure, but I'll offer one theory. It could be that you unintentionally expect your senses to change when you become lucid. So your subconscious manifests your expectations, without any real reason or cause besides the idea that you think it will happen.