Very Late sign. Since the abdominal aorta is in the retroperitoneum, bleeding most often occurs into the space near the kidneys. Early symptoms are abdominal, back or flank pain. It is more common to have bruising of the flanks (grey turner's sign). It is possible for the blood to track all the way up to the umbilicus, but this would be a pretty late sign. Hopefully you would be in the or by then!
No. The abdominal aorta is deep in the abdomen and situated on the spine. A rupture can eventually lead to bruising on the back, days later and if the patient survives, but not on the abdominal wall. Pain is the usual symptom of an aneurym leak and immediate medical attention should be sought.