I have done several trips with school marching bands, cheerleaders, etc.
First, do you have or can you borrow noise canceling headphones? They may be the only way you can sleep with a bus full of kids.
Our buses always makes bathroom stops. Also the drivers have to switch out every 4 hours (by their rules). One sleeps in the front seat while the other drives, so they sleep/switch the entire trip.
I have been on buses where they promised wifi... but rarely does it actually work. We were on one trip where we had two buses. The bathroom worked on our bus but the light was very dim. Come to find out in the morning hours there were bugs coming out the bathroom door. Although the toilet worked the sink did not. Better than the bus behind us that the bathroom did not work at all. Even if you have a working bathroom, they discourage using it because it will stink up the bus!!! So if anyone has tummy troubles, I would hate to be sitting in the back. Try sitting as close to the front as possible.
For motion sickness there is over the counter stuff you can buy or ask your doctor for a Rx. Again, sit up front. Back of bus is bouncier. I rode buses all the time while living abroad and the back always had the most bounce. If you get motion sickness you will want to avoid reading on the bus as that makes motion sickness worse.
If you want to change clothes, change. But you will have to do so when the bus stops for a longer break like a lunch stop. Most of the kids will be wearing pajamas, leggings, sweatpants, etc. unless they are told they can't. Most will bring their own pillow and blanket to use on the bus as well.
Tell the band director not to book the least expensive bus as you will get a crap bus with problems. Trust me on this one. It's worth paying more for a nicer bus where things like the bathroom, wifi, movies, a/c, heater actually work.
