RE: battery
On my first heli I went from a 500 mAh to a 950 mAh battery. Since the battery space was limited I measured the originl battery and found a 950 with almost the same dimensions. Most RC hobbystoresites will give the dimentsions of the batteries that they sell. Also don't forget to try to find one with the same connector as on the heli or get the plugs to make adapters when you get the battery.