We haven't yet dealt with the case where the balls do not hit with the relative velocity along the center-to-center line. The answer to your question depends on what information you do have. Setup 2 of the recent experiment raise the ramp system slightly so that the centers of the two spheres were no longer in the same horizontal plane. The goal of that modification was to determine if a measurable difference occurs in the horizontal ranges of the spheres. However the analysis was based on the assumption that the centers were in the same plane and aligned with the velocity of the first ball. If this is not the case the analysis gets much more challenging. We will be modifying the experiment so the two spheres are offset to the right and left of the line of the original velocity, so the two don't go off in the same direction. We'll discuss how this affects things when we do that.

I'm not sure what the context of this statement is, but impulse is equal to change in momentum, not just to momentum. An impulse of 250 kg m/s will result in a momentum CHANGE of 250 kg m/s.