Ranger, that bark is from a choke cherry tree, not black cherry. Yes, it does give good protection to the back and may even add a little zip to the bow.
When I put the bark down on my bow I cut it close to the bows limbs like Kendall suggested. I used 3/4" blue foam board as a pressure strip because of the irregularity of the bark and selfbow back and wrapped with strips of cloth. I used TBIII to glue them down. It does help to soak the bark in warm water first. It helps to make it more flexable. It doesn't get real soft at all.