It's official. We still get 50% for images exclusively licensed through Alamy. Only 40% otherwise. Check your inbox.
It doesn't say "containing", it says "of".
I interpret that in the usual way- if the artwork is incidental, it doesn't apply.
It doesn't say "that are subject to copyright" either, it says "that are NOT protected by copyright". It's to exclude out of copyright images such as Bill was asking about. They can't be exclusive.