This year's book is one that I believe Blazhevich did from his School in Clefs for Trombones book. It appears that you like his etudes from you comment in 3) above. Two of the etudes that I picked have been used in previous years for tenor trombone tryouts.
From my experience in judging MS tryouts, yes the bass trombones have to play above the staff but that is because they are playing the tenor trombone music with the tenor trombones. They aren't competing in a separate bass trombone section with bass trombone music..
Maybe in working on these etudes bass trombone players can learn to "not loudest splat on the lowest note!!"
If book is poorly written then it is our responsibility as teachers to help the students understand what is written.
I am more than wiling to help anyone that is need of help to understand the etudes. My email address is email@example.com.
Also, if you would like to have a fact based discussion on this, please email me. I am more than happy to discuss it with you in a more live setting than on an anonymous board as you have chosen to do.
Responses are not allowed!