Can something besides gallstones cause pancreatitis?

Many causes. Alcohol abuse is the most common cause followed by gallstones. Trauma to the abdomen, some drugs, a blocked pancreatic duct for a variety of reasons, and congenital conditions may also cause pancreatitis.
Yes. There are many causes of pancreatitis. Alcohol intake, hyperlipidemia and medication are other common causes.
Yes. The most common cause of pancreatitis is gallstones; alcoholism is a close-second. There is a laundry list of very rare causes of pancreatitis including certain medications, anatomical abnormalities of the pancreas, very high triglyceride levels, etc.