I agree with you, the web export is very important :)
The engine will allow classic dialogues, with or without characters portraits, and will also allow for cutscenes (both things are still a bit in sea, so unforntunately I don't have yet too many details on utilities/limitations to give you) and the GUI will be completely customizable. That's to say that the image you have in your mind (I didn't know the game, it's pretty cool!) is quite accurate :)