If you leave the skin on, you'll get off flavors and it will be harder for the yeast to get at the fruit's sugar.
Use a potato peeler.
You should take the stones out for the same reason.
My process for cloning a beer
1. Put on lab coat.
2. Drink beer and take notes.
3. Repeat Step 2 until I have a recipe or pass out.
On deck: Barleywine, Dampfbier, Belgain Golden Ale, Hazelnut Sweet Stout, IRA, Rye-weizen, Wit, Uinta Hazel Clone, Uinta Yard Sale Clone.