Glueless skins?

I bought a pair of Swiss Army issue skis with skins.  ($20!)  The skins have several metal clips down the sides in addition to the tip and tail clips.  There's no evidence that they've ever been glued, but they might not have been used at all (though the skis definitely were).  Do I need to glue them, or will the side clips do the job?

On a related note, is it completely crazy to skin up an off-duty slope?  Doable?  Safe?  I live on the resort, the slopes are closed Mon-Thu, and there are no prohibitions I can find (forgiveness vs. permission, right?).  Any advice, experiences, or words of caution are greatly appreciated.  (I know it's not exactly backcountry, but I wanted some skinning perspective.)