Beleg, If the back of the stave is sound, do not decrown. Hickory is very good in tensile strength, and having a crowned back only reduces the bows physical weight I would recommend Heat tempering the belly of any hickory bow, but even more so with a sapling bow, since they are typicaly narrower than one from a larger stave. Depending on the length and your perferred draw weight, I would not recommend taking down the sides of the bow until after mid limb,(this only makes it narrower). Tiller sapling bows very critically, remember that wood you take from the belly not only makes the bow thinner, but also narrower, due to the back's constant curvature in cross section. Also, make sure that the bows crown is consistent or you will have narrower sections of limb than others. I love building hickory sapling bows!!!!!! hope yours turns out.
Cody