When you get into the sixtuplet rhythms toward then end of the excerpt, you see the backsticking notations.  Over tne first left hand accent after the right hand backstick, you see a + over the accent.  What does this mean?  (I assumed some sort of cross stick, but it doesn't show in any video I've found thus far...)

This indicates the right stick to cross over the left stick. Not backsticking, just a little crossover on the snare. We eventually took this out, but for auditions will plan to use stuff as written in the book as much as possible.

That's what I assumed, I just wanted to be sure for the auditions!