Does my son need surgery if he swallowed several quarters and nickels?

Possibly. If this happens call your doctor or go to the er to be evaluated. Especially if anything else may have been swallowed.
Depends. The primary worry with a foreign object injestion is whether it sticks in the swallowing tube half way down and blocks it. That could cause spit & fluids to be sucked into the lungs causing pneuminia. If they made it into the stomach, they may or may not be able to pass into the intestines. If they do they will pass thru in 3-5 days. Xrays can locate them. Some require the coins be retreived in or.