protein shakes & lots of carbs. Don't worry about cutting or anything you'll lose lots of fat & a little muscle while in Basic. As for strenght, the APFT (fitness test) is more about endurance, usually the lighter guys with less muscle do much better. You should concentrate on doing push-ups, sit-ups & running. The best thing for improving them is doing, push-ups, sit-ups & running.
Supertech69 <----ex SGT 5yrs Active duty