There won't be any scripting in the demo, perhaps apart from hacking the UI that communicates with the engine via the javascript. But that functionality is mostly designed to alter the environment, it's not a scripting in the classical sense.
In the game there later will be a possibility to script game objects and stuff, but much of that has only to be determined yet. We will have the same interfaces exposed as C and javascript (and possibly others), so technically some teams would write their game modules in C/C++ while others may settle for JS or to combine them both. Though ultimately I'd like a scripting language that can be more effectively compiled after tuning the scripts, for performance reasons.
Also, there will probably exist a developer version with an SDK and with additional support on server side for creating alternative worlds for the games.
On a slightly related note, do you import physics attributes though Collada?
Not yet, but since it's supported in Bullet physics we probably will soon.
