There will likely be an athletic trainer present given that football is a contact sport. Introduce yourself to the ATC and see if he has any requests about where to put your truck and stuff. Also go over how he will notify you if your assistance is required. For what it's worth you don't really work with the training staff, they can take care of 99% of the injuries themselves and will do so. I currently work as an assistant athletic trainer and my boss gets a bit peeved when our paramedics are milling around the treatment area throwing their two cents in about how to treat various injuries.
If you end up on the field, listen to the ATC's instructions. He is more than competent in spinalling someone and things of that nature. He will probably already have manual c-spine, don't bother having him relinquish it or anything like that. With football helmets you can usually leave it on along with the shoulder pads to maintain a neutral spine. The facemask will still have to come off, but the ATC should be able to do that for you prior to transport. If you have to transport a player, the ATC will likely want to ride in so as to assist the ED staff in removing equipment.