Unless you have to get things on the shelves that are already there on a daily basis, I would get some sheets of plywood/insulation/something to stand in front of the shelves and make that a useable area. Even if it's just for a design wall. They have sets of wire baskets/drawers that will fit under tables and work well for fabric storage. As far as not being able to get rid of the stuff, my method is to do a few things at a time. I look at it decide if I want to keep it and then it either goes in the charity basket or the trash. When you do 3 or 4 items a couple times a week you don't really notice its gone and suddenly there starts to be extra space.