3) What does it feel like to have a nosebleed?

Gross. To be honest it feels no different to having an impossibly runny nose, except it's blood instead of liquid snot. It's when it dries and you have crusts of dried blood in your nasal cavity that it becomes really unpleasant. :D

1) How big is the gap between Asperger's Syndrome and high-functioning autism?

One has slightly different features to the other.