You've answered all of my questions satisfactorily
I now have one tiny suggestion, that you indicate somewhere on the score that the performer is to decide on the tempo. I know this may be written elsewhere in performance notes, and you may tell the performer - but it's my personal opinion that it would look nice to have it on the score
As for your choice of 11 and 15, and think that's a perfectly good reason to use those numbers of bars, I like it.
Congratulations on an interesting and thought provoking piece
