Here at the farm we use 18-20 square feet per bird with 20 being optimal. We also use peepers/bliders/specks as well to deter feather pulling/pecking. We set our posts 10 feet apart and bury our fencing(1" PVC coated chicken wire) a foot in the gound and a foot out like a L underground. Top net we use 2" heavy knotted nylon netting. As far as cover if you plant corn, sorgum, sunflowers, or a similar seed early and have it 1/2"-1" round by the time you let the birds out it will continue to grow and provide good cover. We also plant oats and wheat in with our corn and sorgum and they seem to hit that first and it gives the corn and sorgum more time to grow. We do not put our birds out until 5-6 weeks old. At 1 week old we start to lower the temp of the brooders and by 5-6 weeks the temp in the brooder is within 10 degrees of outside so we just shut them off or put the birds in the outside pens. Make sure you have plenty of feeder space and feed at all times for the birds as well as water. They will get very agressive if food or water is absent for more than a couple of hours. Good luck. I buy all my fencing/netting from 3T products, they are the cheapest I have found and are very helpful.
www.3tproducts.com