I don't know if I'm just an easy case or what, but after I had my gallbladder out I had no problems. The only thing different was that I didn't have any more pain in my right upper quadrant and I no longer felt the urge to vomit all over everyone anymore. I had really bad diarrhea for years and they told me this probably wouldn't change the frequency of my diarrhea; they were right. It might take a few weeks for your system to work out the kinks, but it's one of the most-performed surgeries in the U.S. and is considered pretty minor.
My surgery was quick; I was out of the hospital within five hours and stayed at home from work for a week. You won't be limited as to what foods you can eat, except you might have a hard time with really greasy stuff (but doesn't everyone, even with a normal digestive system?). Some people notice they have increased diarrhea after their gallbladder surgeries because more bile is being pumped directly into your small intestine from the liver, but it usually clears up. Some people do take medication to control the diarrhea afterwards, such as Welchol or Questran, and some control it with simple calcium citrate supplements.
But like I said...you likely won't have a lot of problems. I have never heard of an increased risk of stomach cancer after gallbladder surgery. Anyone who lives long enough will get cancer anyway (not sure if that's a comfort to you, but it's true!). If your gallbladder is causing you pain and nausea and other problems, it will improve your quality of life to get it out. You should always feel free to get a second opinion from another surgeon before you go under the knife. Most doctors actually encourage this.