It seems to me that everyone is different. While it seems everyone on here now suffers from chronic diarrhea, I had my gall bladder removed under emergency circumstances a little over a month ago, and my digestion has gotten better and now I no longer have to run to the bathroom. I have Crohns disease, that seems to have improved since my gall bladder removal. So, it seems hard to say if you will have the same problems everyone else here seems to be having. Personally, I seem to be fine without it, and can now eat foods that before would bother me. But maybe I'm an isolated case.
You don't have much time to do research since your surgery is tomorrow. I'm sorry I don't have better advice to give you now.