That is adding to the meta-model :-P but yes, we are doing that as well and we have seen that the moose panel is not happy with our subclasses. How do we add the meta-description? Is there some reference text on this?
Easy. Look at the class side of existing classes (e.g., FAMIXClass)
The ID is for objects, not for types and they are used basically for reference management. It is the responsibility of the exporter to properly create and manage the ids.
So, these IDs are only used in the import process and then discarded?
Each moose element has an ID. But you should not care about it. Moose manages this for you.
Alexandre