One of my cats is super scared, former feral. I medicated her during the drive (5 hours) to the airport and it had worn off by the time we checked in but she was still pretty calm after it wore off (all with vet approval). So the medication did not affect breathing on the plane but at least the journey started off mellow.
The water and food was silly but required by CX for my trip- all it did was get all over the crate and for one cat, he upended the crate cushion and it contacted the water bottle and wicked out the water...sigh. I bought custom-sized cushions that perfectly fit the crate, they slept on them in advance of the trip (still use them under the bed) but one cat spent the trip under his cushion.