Official Modding Support

So although SD has officially embraced and encourages modding, that popup in the editor tools says it's unsupported.  So what level of encouragement are SD going to give?  Meaning, will there be official documentation on what to use, where to use it, when to use it, how to implement, etc...?  Is there any documentation now about what XML to edit, when to edit it, why to edit it, what the tags within represent and what it affects, etc?

I also read somewhere (sorry, can't remember) that the scenario was done with the same modding tools we have available to us, will there be documentation on how it was created, and how (if) we can create our own scenarios?