RE: 2 cell or 3 cell
It would largely depend on the plane you would fly it in. A 2 cell wold give weak performance -- less than an 8 cell battery would. A 3 cell Li-Po would give youi good performance. If you use 3 cells you may have to prop down to make sure that you do not ec=xceed 10 - 12 amps into the Speed 400 motor.