Rawhide would add very little, if any, draw weight. Sinew and wood backings like hickory or bamboo will add a good bit of weight. As for tightness, most people probably string the bow so that the string is about 5-6 inches from the handle at brace. Brace height isn't carved in stone, you may have to adjust it up and down a little bit until the bow shoots like you want it to. Too low can make arrows fly left and the string will eat your arm up, but gives a bit more arrow speed. Higher brace height can stress the bow badly and slow the arrow down, but is more stable and forgiving. You just have to play with it til you find the best compromise.
