I am making a 9X13 sheetcake...using a edible image. This is for a dance club party and I am using their logo..in black. It has lots of edges so I do not want to put a border around the image...Should I cut it out? Also I am putting it on buttercream...do I wet the buttercream after I smooth it with paper towels before applying the image?

As long your BC is close to the same color you shouldn't have to cut it out. And NO do not wet the icing before placing the image on; just make sure your cake is at room temperature so the adhesion takes place, your icing sheet will blend nicely into the icing after a while....you won't even notice your edges (of course that is if your BC is closely colored to the sheet).