Definitely save the rinds, they are soooo good in soups! As for trying to determine how fresh a store bought parm may be, check the wrapping. Was it hand cut and wrapped or does it look commerically wrapped? Commercially wrapped cheeses can use a thicker plastic that they drop in a shrink tank (a hot water bath) that seals the plastic to the shape of the cut. A real hand wrapped cheese will be recently cut and will have a "sell by" date on it. The plastic film used in real hand wrapped cheese is more permeable (i.e. tiny holes so the cheese can breath). Ideally, you have a cheese store in your area, or a deli or specialty food store that can pry off a wedge for you.
