Good luck with your surgery next week! If you have a tendency to have nausea, be SURE to tell your surgeon. He/she will want you to have anti-nausea meds at hand, because retching and vomiting are very hard on your wrap, and can actually cause it to fail. Take it seriously.
Yes, Ensure and things like that are good for your first couple weeks. I've heard of people who blenderize soups to make everything liquid, and enjoy that. Be sure to ask your surgeon for suggestions.
I was only in the hospital overnight. I went in one morning, had the surgery about 10AM, recovered during the day and overnight, and was released the next morning about 10AM.
Try to get your surgeon to write a script for pain meds in an elixir (liquid) form. It's amazing how they tell us to only take liquids, then give huge solid pills for us to swallow! Insist on liquid!
Also, get some liquid Tylenol (adult strength) to have when you don't need the narcotic pain med. You'll probably need the heavy duty kind at night longer than during the day.
As for dumping syndrome...it's a temporary problem, and will resolve once your stomach adjusts to its new cofiguration.
I second (or is it "third") the motion that you should get up and start walking. I was walking the halls at the hospital whenever I got up to go to the bathroom. A night nurse gave me that tip, and it wa a great one.
I found the more I walked, the less my shoulder hurt, and visa-versa.
Again, good luck with your surgery! Glad you've joined us.