What information is imported into Unity?

Hi I would really want to know about what data about the meshes, rigs and animations are imported into Unity. And Iam talking about more technical aspects than "bone hierachy", "curves", etc.

Iam tired of googling it without a clear answer. What I really need to know is, for example

Does unity uses the rigs as blender uses it, or it bakes the animations into the deformation bones

-Does it import non parent relations between bones, like drivers and constraints?

-Does it import vertex groups, if so, how do i use them?

-Does mecanim use the extra bones (control and manipulation bones) or they are just junk in Unity?

I think I already made my point of what kind of information Iam looking for, you dont need to answer the questions, but at least point me in the right direction. A book, a wiki, something thats not just "set this things, save it there, set those other options and there you go" because when something isnt working I dont really know what is going on or what could it be that went wrong.