I do this for land developers all the time. I shoot with a nikon 200 and use two lenses. 1. 70-330 2. 1-70. Both work great for this. The helicopter can fly only as low as 500 ft, but the lower the better. I have gotton the bests shots from 500ft and having the pilot move back so that i can get everything in the shot. I also use google earth to set up my shot prior, then give the pilot the gps cords.
Because of the price of the helicopter I have also used a kite check out some of these.
Kite Aerial Photography - KAP. This was a hobby that turned into a money maker for me.
hope this helps.