I highly recommend NOT using a screen on the BS oven, or any oven for that matter. Pizza screens fundamentally change the bottom of the pie as the bottom surface never comes fully in contact with the stone, and not for the better, IMO. They do serve a great purpose, though, and that is a holding surface while the pie cools a bit before slicing.
I can't recommend the Super Peel highly enough - I wouldn't be without it and makes launching pies easy and trouble free with no change in the shape of the pie or movement of toppings during launch.
I did an extensive review of the BS Pizza oven, with a bunch of tips that may be helpful to new owners:
http://mooseonfire.com/home/2015/1/4/product-review-the-blackstone-pizza-oven