Quote: "will this be powerfull enough that when you open a door to a flooding room, water will pour out of it? or will we open doors to be greeted by a brick of water being held back by an invisible wall :/
Or, can you only make it so the water is at the same level throught the game? "
This was answered and discussed in one of the first pages, as well as in many other FPSCX10 threads. The water is just one flat "level", kinda like a plate that goes through the whole level.
You can change this level to what ever you want, event make it to change (rise/decrease) while in game, and change some graphical features of water as well. If player or object is under this "plate", the water physics activate (floating, swimming, some visual effects and other pre-set options). Other objects are directly effected by the water level when touched by it.
I don't think we'll be seeing water like you descriped for a long time, since it would require tons of different things to be calculated, created and edited in real time. Dunno if we even have technology to emulate something that complicated yet.