I would make sure there's a high level NICU at your hospital and that they've been monitoring the baby via ultrasound for any signs of bright bowel, possible meconium illeus (Bowel Obstruction). Otherwise, IMO treat her like a normal baby who just needs a few extra things to keep her happy and healthy -- vitamins, enzymes, nebulizer and chest physiotherapy.
Also being that it's cold and flu season, make sure any visitors wash hands before holding the new baby. Being that your older daughter is a toddler --- aka germ factory... <img src="i/expressions/face-icon-small-smile.gif" border="0"> may want to try to keep her from touching her new siblings face, get her in the habit of washing hands, using hand sanitizer as well. First thing any of us do when we come home or get into the car from the store, etc. is to use hand sanitizer or wash hands.