1. Neither. Some people find it impossible to DILD but find WILD easy as cake, some people see it the other way around. Try different techniques and combine them.
2. Yes.
3. Waking up from an SP can feel like waking up from a dream. It just happens. Lots of guides and forumtopics on SP around here. Use the searchfunction.
4. Yes...it's answerable if that's what you ask.
5. Again, lots of guides cover this. Read this: http://en.wikipedia.org/wiki/Hypnagogia