Some more developer answers from the official Nival forums (excluding info already covered in the Fabrice interview):
The map editor will include campaign editing functionality. (Previously, Nival refused to give a definite answer on this issue.)
Eventually, there will be an option to disable the camera flyby in towns.
After a bunch of new multiplayer maps appears in the second patch, Nival will start making new maps available gradually without any relation to patches.
The second patch will include descriptions of creature abilities.
The editor will include two new map sizes - Small (72*72) and Huge (216*216), which are currently unused in the game.