When you have the sleeve done, what happens to the staples and stomach, do they stay permanently?

The staples used in endoscopic surgery are permanent, made of a body-safe material, and of millimetric size. With the body's healing process, they are covered with tissue.

the stomach does not "grow" from new, there is a misconception about this, the stomach is an organ composed of several muscular layers, the muscle is able to stretch and return to its original size, if the patient post sleeve does not take a proper dietary regimen is possible that this muscle will stretch and lose the ability to return to its size resulting in increased ability to retain food, defeating the purpose of the surgery to decrease the size of the stomach to decrease the capacity of the stomach.

The staples hold the cut edges of your stomach together so healing will occur. Much like sutures/stitches hold the skin together so a laceration will heal. Unlike stitches, these staples are permanent. They do not dissolve nor are they removed. They are very small though. Only a few millimeters in size.