Do an endoscopy. Stomach wall thickening may be due to chronic ulcer  for which you may need medications. Gb polyps need to be removed especially if they are more than 5 mm and if they are multiple, because the chance of cancer is high.  Unfortunately you have both indications. Gall bladder surgery can be done through keyhole, even scarless(single incision laparoscopic surgery). Can be done as a day care procedure, that is same day you can go home!