Hey guys I can confirm a few things for you as I use the 2.5A motor controller here at the shop quite often.

The controller does have a 5V regulator on board that supplies the L298 with the voltage it needs as long as you provide (as @bstaehling mentioned) 7V or higher. Only one power line and ground required to attach it from your v4 (fuse protected) or directly from your battery. Just remember to tie all the grounds together.

The controller also accepts 3.3V TTL logic and works flawlessly with the V4 providing the inputs signals, just hook up 4 digital pins from the v4 to the motor controller input signal lines and optionally 2 to the enable lines (pwm h-bridge control) and you are on your way.