[ic-racer]

Does the 0 or lower numbers on the filter pack effect the highlights, and the larger numbers effect the shadows?

Yes, more exposure with the # 00 filter will make the highlights darker, whereas more exposure with the #5 filter will make the shadows darker. (do you not have the #00 and #5?)

Realize that in both cases above, the mid values will also get darker. So, it is up to you to determine if you can zero in on a good print better that way vs using the individual numbered filters alone.