Have WOTC said exactly when the Tiamat/Cult of the Dragon story begins? Will it be at launch? If so, how do you handle a Forgotten Realms game without having a setting book? It sounds like a pretty epic story, so keeping it to one area like they have been with the Encounters modules of late...
Say you are standing in a room, and it widens 2 squares away from you, if you casted a blast 3 spell, would the remaining part of the area go into to wider area or would it just stay in it's straight line path. I'll try to draw a diagram here...