I agree, when you cut it try to get one clean cut or multiple cuts in the same direction DO NOT saw back and forth this could increase the chances for infection. To attach the frag to a rock I use a needle and thread. I go through the base and tie it off on to the rock, this seems to work well. Also try to put the frag in the same conditions as the mother, same water movement lighting ect...The baby coral should attach in about 2-3 weeks maybe even sooner.
Have fun
Tony