You did not say what position you wanted to try out in football. So, with nothing in mind, you can not go wrong with Cleans. Try PowerCleans (from knees up) or straight up Cleans (from the floor) will give you explosive strength from both 2 and 3 point stance. If you are willing, do Clean n Jerks. They will build up top balance. Be very careful about full front squat when cleaning heavy, it is a good way to push a knee out for results that only an Olympic lifter would be attempting to achieve.
You can't go wrong with the basics of Cleans, Squats and deadlifts for football. Try some bounding for power too. If you have access to an indoor pool, you can bound in the water. Sounds silly, but the deeper you go, the more resistance to get your torso out of the water. All without the knee strain.
What ever you do, stay off machines that isolate movement, you want to get all the benefit of moving weight through your connective regions to gain real strength. Train the trunk, but don't let it be the be-all of all your training.
As for eating, eat right now (even thought your young with a high metabolism) and you won't have to pay for it later.
Good luck.