Translating velocity to local directions?

If you use the Get Velocity node on the actor you should get a world aligned vector that describes your speeds.

The sum of the 2 (x and y) would be your total speed in that forward direction I believe.

which would or should not exceed the maximum set in the movement component.

you can use the value of X (positive or negative) to determine your heading, coupled to the value of the forward vector.