I was told I have a mild borderline bile duct prominence what does that mean?

Probably nothing. A dilated bile duct can indicate passage of stones or pancreatic disease or cancer but a mildly prominent duct may be normal. You should have your study reviewed by a gastroenterologist to determine its significance.
Depends. Your bile ducts can become enlarged from stones or tumors or scarring. See gastroenterologist. Mrcp can image the ducts. Gi doc may do ercp. See radiologyinfo.Org for mrcp info.