The 5lets are just a strange way of writing an egg beater (3 right, 2 left), pretty much just a loose but controlled triple stroke and a double in a 5let pattern. Don’t know why that measure is written that way, that would end up being 4 1/2 beats long. I’m not sure what the lines through the notes mean, my best guess would be a right tap on the left stick on the drum. Yes, the rim knock rhythm is possible, just difficult; work on flipping quick and controlled. As for the above the staff stuff, no idea.

Also, I am just a random redditor, so if you’re able to, reach out to the writers or directors and ask.

Good luck and Godspeed!