Finished going through Karazhan Key questline and figure I post up my notes on it. Basically its a lot better than the Onyxia key questline in making sense.

Karazhan Key Quest
Arcane Disturbances - Get two water readings they are each in different Master Cellars that are in the ruins of two diffferent buildings nearby the quest giver
Restless Activity - Kill Ghosts around Karazhan (not Unliving Residents) for 10 Ghostly Essences
Contact from Dalaran - Head to Dalaran to talk to Archmage Cedric (he's at the farthest north part of the sphere)
Khadgar - Head to Shattrath to talk to Khadgar
Entry into Karazhan - Head to Shadow Labs for the first Key Fragment (found next to Murmur in an Arcane Container to the north of him)
The Second and Third Fragments - Second Key Fragment is in Steamvaults in the water just south of the first boss in the north most part of the water on the bottom. Third key is a short way in Arcratraz after the first boss (the next room up the ramp on the right side)
The Master's Touch - Complete Black Morass and speak to medivh
Return to Khadgar - End of the key questline, just return to Khadgar and he gives you the completed key.

BTW on all the parts you can hold the instance open and have people rotate through to complete the quest.

Good information, but not really a topic of discussion.