I'm bringing this up again, the documentation has somewhat stalled. There are quite a few new functions that need documenting and several functions that have been removed.
When you commit new Lua-enabled code, please take the time and add documentation, too. I'm asking nicely now, but I'm seriously considering rejecting any PR that doesn't do this in the future.
I did it

It would probably be useful to add the capability to InfoDump as well, particularly for large projects like worldedit.
I'm not following you here. What has InfoDump in common with this? We need the MCServer's API, and that means APIDump. InfoDump does plugin descriptions, there's nothing in the ZBS to consume such data.
Interplugin calls. e.g. handy. Might be useful to see if Zerobane studio can recognise them. if not theres no point.
Interplugin calls are handled using strings, I don't think there's any way for ZBS to recognise those:
local Result1, Result2 = cPluginManager:CallPlugin("Handy", "FunctionName", arg1, arg2)
Ok, don't know that much about how ZBS works so I had no idea whether it could recognise them.
I'm resurrecting this thread from the dead. The documentation has become lacking again. There are many new classes that have none of their functions documented (projectiles, entities). I therefore urge everyone to write documentation together with writing code. And to practice, we should all try to complete the documentation. After all, it is even used while developing plugins - ZeroBrane Studio reads it and provides code completion and infotips based on it.