The bold comes with a basic holster...It's not leather (koskin I think). Though you can buy the leather one from amazon.com for cheap. And the official store sells an exclusive "premium" leather one.
As for screen protectors, you cannot beat invisible shield or BSE... Yes they are a pain to put on but last incredibly long and are super protective from scratches.
And yes, the screen will get scratches no matter how much you take care of it. Even from carefully sitting inside your jean etc... or cleaning using a cloth.
It's really a scratch magnet so you should definitely get a screen protector. You can get cheap, easy install ones that don't last as long or pay a bit more to get one that require time and patience but last really long and give great protection.
My invisible shield protector has saved the screen numerous times I accidentally put my keys in the pocket where the berry is.
But once again, the holster that comes with the device isn'st leather. It's a cheap basic one. You can check the official store, there are 3 different holsters you can buy. (basic, leather, and exclusive premium leather).