What is, or could be, a 1cm possible cystic lesion on head of pancreas verses dilated distal common duct? Should I be worried?

At your age, no. Lesions on the pancreas can be serious, but in young people are usually not. It may be a cyst or may be a dilated common bile duct due to an obstruction such as a gallstone. You should not be too worried, but you do need to get it further evaluated, usually with an endoscopic ultrasound exam or a repeat scan.