Id say, before you go thinking of molding the helmet, you need to get further along on it. Youre looking way to far ahead. Concentrate on what you have in front of you now and when thats done, move on to the next step. Sculpting helmets and making molds, although related, are two totally different art forms. Baby steps, my friend.
Also, 1 qt of silicone will not be enough. I usually use about 2/3 of a two gallon kit on most of my helmets.