Haven't played an assassin to hero and don't really want to...

How long does one have to be stalked, or does that really matter? Does it matter if you can see them nearby while being stalked?

What are the actual affects of the trance? Clearly they melee like crazy.

Is there a warm-up time before it kicks in, and if so how long? How long does it last? How long until it can be used again?

Any weaknesses or vulnerabilities that can be exploited against one in trance, or is it pretty much an avoid-them-if-at-all-possible-until-it-fades situation?

Lastly, any way to know when or predict trance other than starting a fight and finding out after you just got ground controlled to death?

Thnx.