The API will be mainly unchanged, that means: we do not have any plans to change it, but if we'll stumble across a problematic or missing part, we may make appropriate changes.
The scripting should work mostly to the same extent as with K1 with 2.0 and new IntelliJ plugin, provided that we'll not discover significant obstacles during implementation. So far the implemented parts are quite compatible, but there are some work left.
We do not plan any specific improvements or new capabilities for the 2.0 release, the first aim to make it work as in K1.