That's a good size room toecheese. Looks like you got the whole family involved too...
Screens... I used my wall with 2-3 coats of Kilz 2 and then 2-3 coats of Misty Evening Gray with lots of sanding in between. Looks good to me, but I suspect a nice fabric screen would probably improve my picture some. I'm just happy enough with what I've got. If you are being money conscience then the DIY is much cheaper. Money no object - buy one.