A good poly should have a firm/hard twist and not be soft and mushy. To be honest the stuff I've gotten recently needs to be hand retwisted (Later, I'll see if I can't post a before and after picture from the rope I'm working on right now) to get it hard enough. It needs to have a good lay to it though so that your body isn't twisting up really bad. It also needs to be a split film or fibrillated (same thing I think) and not monofiliment.
As far as curing, thats just untwisting all your strands and letting them sit for a little while to make sure they don't twist back up on you.