For A123, you should setup the jumper for 5-cell NC or NiMH batteries.

I will plug the Flap servos in the Powerbox, as they tend to require high currents when in use.
Actually, you just need 1 servo directly to the receiver. Others can go to the Powerbox to benefit from the regulation. The ECU to the receiver should do the trick, but lets say ECU and the gear to the receiver to be safe.

Good Luck!