definitely prewash all fabrics to help prevent bleeds and get rid of leftover chemicals used during manufacturing processes......actually cutting 112 pieces all at once won't be that bad....since they are all the same size, you can fold your fabric lengthwise so you have the selvages together then fold once more so you have 4 layers (being very careful when folding to get a crisp fold, I use a ruler)....you can cut either the 6.5" or 3.5" and then cut the other dimension....it will go quite fast....cutting a 6.5" strip will yield approx. 10 3.5" pieces and if you lay 2 strips on top of each other you will reduce your cutting time by half!