Thanks PP, at first I had a wry smile at the fact that you had this under the Thread Title "Daniel made simple" as it seemed at first glance to make matters more complicated !
But the ideas you reference , of the Book we have in our Bibles as being a collection, makes sense of so much, especially the language change, a section in Aramaic, then back to Hebrew which I could never fully understand.
It seems then that there never was an original "Book of Daniel" as we used to think, but that a lot of Texts existed that used the same literary device to interpret the vicissitudes that occurred to Israel and Judah in different periods, every new Ruler who came along and subjugated them was explained using this method.
And so an attempt to reconstruct an "Original" Book of Daniel is doomed to failure.