How can I cut a long skirt and make a short one?

I have a 40 inch long 5-tiered skirt and I plan to cut off the lower 3 tiers to make it a mini or a knee-length. I need to know if I can use the extra to make pleats and if I can make pleats how do I attach them with the mini? Also when I bend down the hemline on the backside rises up quite a bit and exposes the back of my thighs and leaves it open for pervs. Is there a way to keep extra material on the backside so as not to expose my back too much while bending ?