You can take 529 distributions for qualified expenses without incurring taxes and penalties. Transportation is not a 529 qualified expense. Room and board is a 529 qualified expense for students who are enrolled at least half-time. Your son's school provides room and board COAs for different living arrangements, so use the room and board COA provided by the school that is most appropriate for your son's situation. Besides tuition, certain fees, books, required supplies and equipment, and room and board, "the purchase of computer or peripheral equipment, computer software, or Internet access and related services" can also be 529 qualified expenses.
See Chapter 8 of IRS Pub 970:
Note that the 529 distribution taken based on the tax-free scholarship funds that your son receives will need to be reported as income on the tax return of the person to whom the distribution is made payable.