Be sure to buy the pants loose (get some with a string), because you'll have some bloating, and you won't want tight elastic, either.
Take Gas-X with you to the hospital...it's almost impossible to get it--it nearly took me an act of Congress. Keep any such supplies tucked away in your suitcase, as if it's surrendered to the powers that be, you'll be at their mercy again.
Don't drink out of any straws...they introduce too much air into your stomach. The hospital kitchen won't know that. They gave me carbonated soda on my first tray...go figure. They haven't a clue.
When you first get out of surgery, you'll have difficulty swallowing water, but give yourself a little time, and you'll be swallowing it just fine.
A night nurse gave me the best advice ever...WALK. She advised that I should get out and walk whenever I got out of bed to go to the bathroom. I walked laps around the hospital hallways, and at home I walked from room to room. I had a treadmill, so after a week or so, I got on it and walked slowly at first...increasing the speed as I felt better. It helps get/keep your strength up.
Good luck tomorrow! You'll do just great. If you get a chance, read the post on LeAnne's thread where I pasted my post surgery forum entries.
We'll be waiting to welcome you to the Wrapped Club!
Have a Happy Hospital Stay!