RE: Better Turning Radius?
Try getting a new servo. The 3003 is a cheap plastic geared servo with virtually no power. The Hitec HS-645MG is a great servo with tons of power. The Futaba 3305 takes too much energy from the batts for the same power.
Also, getting a 5-cell hump pack will help a lot. I use the NiMH Venom 5-cell hump pack from towerhobbies and love it.