I just had a Gastric bypass
12 days ago. YES they leave your stomach in place after making the pouch. The stomach still produces stomach acids. These acids meet with the foods you eat in your small intestine
to aid digestion. Remember the stomach is only a "mixing bowl" no actually fod absorbtion takes place there. So yes, you get to keep you stomach!
I had my surgery 12 days ago and have lost 25 pounds. It is not easy. Learning how to eat is very difficult. There is quite a bit of pain while recovering from surgery. I didn't start feeling anywhere near normal until 10 days later.
I wish you luck on your journey!