there is never food deducted from your pay.
As for using your 529.
Keep in mind. That while there are some expenses that would be qualified expenses at the USAFA, the USAFA itself is not a qualified educational institution in the eyes of 529 plans and the IRS. Therefore, you cannot use funds from a 529 plan tax free.
you can withdraw funds and use them, really for anything you want, but you will be taxed on the earnings portion.
the next part about how to actually pay back the USAFA for the items is an issue that I cannot help you with as they did things differently with my son back in 2007 than they do now.
But most importantly, keep in mind that when you withdraw those funds, you will get a 1099-Q and have to pay tax on the earnings portion.