1.-From what i have seen on the json, the weapons that are crafted as throwing weapons are in the melee json. But i thing that more to give them the weapon caracteristics (since rocks for example are coundted in the ammo section)
2.- if i remember correctly the damage of the throwing weapon comes from the result between its weight and volume, the ones that you see on the description (for example the cut of the throwing knife) works as bonus/chance iirc (dont trust me on this last one)
3.- i thought that was already coded, since even rock or nails when you select the option to throw they get wielded by one and then thrown (or just held in case you cancel the throw)
And can you tell us when you release the weapon, i really like throwing stuff on the game, sadly there arent any good effects for throwing weapons per se.