Hypnogogic imagery is something that happens often when you attempt to WILD, however it does not always happen. Some people experience hypnogogic imagery almost every time they attempt to WILD, others rarely experience it.

I have never heard of "rolling" out of your body during sleep paralysis, but then again I haven't read a lot of WILD tutorials. Usually forcing yourself to move causes you to break out of sleep paralysis, which will result in you having to start over again.

If you haven't already, I suggest you read through Mancon's In Depth WILD Guide for more detailed instructions on how to WILD.

I hope this helped clear things up somehow.