Fixtures, any kind of personal property that is permanently attached to a house (such as drapery rods, built-in bookcases, tacked-down carpeting or a furnace), automatically stay with the house unless specified otherwise in the sales contract. But you can consider anything that is not nailed down negotiable. This most often involves appliances that are not built in (washer, dryer, refrigerator, for example), although some sellers will be interested in negotiating for other items, such as a piano.
If space is tight, consider using a panel saw to cut large sheets down to smaller sizes instead of setting up to handle them full size. When building overhead shelves, consider that a comfortable vertical reach is from 77-in. to 88-in. Normal horizontal reach ranges from about 15 1/2-in. to 20-in.