So what i don't want is... ether the board or Arduino to be lacking supply amperage or to provide to much voltage.
It is the power supply's responsibility to control voltage. The design of the breakout board limits the amount of current that if can handle. The motor determines how much current it needs, and, therefore, the amount that the board needs to handle.
However the CW/CCW, ON/OFF, and LOCK pins which will be connected to the arduino should not exceed a supply voltage of 5 volts if they supply at all and demand more amperage then the arduino can supply (in order to prevent Arduino failure). I assume these pins are 5 volt activated. Would you happen to know the amperage rating for an Arduino Mega.
The Arduino can supply 200 mA, over all the pins being used. The control pins, like CW/CCW should draw very little current.