Is there always some pain when touched or rebound tenderness in appendicitis? or does that come later, when it's already progressed?

Not always: The physical signs and symptoms of appendicitis depend upon the location of the appendix. A small percentage of humans have a "retrocecal" appendix meaning it is buried up under the cecum with the tip up in the right upper abdomen, often under the liver . Tenderness and "rebound" may not be present, even with well-advanced appendicitis, as the peritoneum is not irritated.