Position, velocity and acceleration stand in a direct relation.
If you have the function that describes the position, then the derivate of that function will give you the function of the velocity. The derivate of the velocity function will give you the acceleration.
So that you get here:
X= t^3 - 12t
V= 3t^2- 12
For finding the initial values, just insert t=0 if you suppose that the initial moment is when t=0.