Questions for tumors in liver ?

My Mom is 72. She has high cholesterol (taking Lescol), and more recently, developed high blood pressure. Last year she was found to have a AAA when she was being treated for recurring abdominal pain. She had it successfully repaired, but was found to have vascular disease in both legs. One artery required a stent. Since then, she has had recurrent, sometimes severe abdominal pain still, with lower back pain. She was recently diagnosed with gastritis, but meds worked only intermittently. So the doctor ordered blood work again. Blood work came back showing signs of bile leak from the liver. She was sent for a CT. Dr. just called today to tell her that she has tumors in the liver. She was so upset, she didn't ask any pertinent questions - just listened to her doctor tell her that she had contacted an oncologist, who recommended a PET scan be done. Mom was told she'll be called to let her know when to go in. My question is - what are the questions she should have asked? I am calling her doctor tomorrow to discuss her case (as she gets very scared and emotional when trying to talk about what's going on). Some thoughts: Why PET and not biopsy? Does doing the PET vs. biopsy indicate the suspected severity (or lack thereof) of her condition? Is it normal to have an oncologist on board at this point? Is this a sign of where she's at? What are the possible scenarios (good and bad) of what her situation is? Other ideas?