2) What are the exact mechanisms MC uses for album analysis? What parameters are checked? When is album analysis started/triggered?
I'm not the most knowledgeable on this topic, but I do know that "album analysis" centers around the directory that the files are stored in. In general, if a collection of files is in the same sub-directory and has the [album] field set to the same value, then that collection of files is considered to be an album.
I believe that in order to produce an "album type = several artists" there needs to be more than one [artist] value associated with this album. I thought that the "mix album" followed from this, but I'm not sure of that.
It seems to be triggered any time a file is moved or imported or "updated".
I'm certain that there are details working here that I'm not aware of, but I'm pretty sure that the above in and of itself is correct. If not, somebody will probably come by and correct me.
-JB