I'm guessing you're referring to keeping your back, butt and legs aligned and not resting in the "up" position. Really, you can do what you want (TECHNICALLY), so long as you don't break the three magic rules:Changing hand position actually changes the muscles you are working during the exercise. Hand closer to shoulder width works shoulders, while a wider position works your chest. Both will work your triceps. I recommend using your stronger muscle group and switching if think you can get a few more.
And as for resting officially you are not supposed to rest in a "peak" position.
1) Don't touch the deck with your body
2) Don't take your hands/feet off the deck
3) Keep your back, butt and legs aligned
Breaking those rules or running out of time stops the pushup portion of the test. Nothing else (legally).