If you hate cracking these guys open just find one that has done the work for you! A month ago I ate one raw on site because I didn't have a bag. It was up on a kelp stalk which I found weird so I poked it. It immediately sacrificed a claw so I said ok I guess I'm responsible for eating this thing now... Too salty and watery and apparently potential for parasites (whoops). The claws are loaded with fluid so give them a good press during frying. Also before cooking reach under the shell and scrape the gills off. Just like other soft shell crabs everything inside is edible but maybe avoid the tiny stomach sac right behind the mouth. The story tells where to find them and how to deal with them but don't actually spend time looking because it is a very rare occurrence. Literally the best and easiest single thing I've ever caught and cooked on my own.
When steamed the meat from those crabs is incerdibly sweet, how was the meat when fried? Is it hard to clean the legs of meat once fried.? Its a bitch when steamed because theynare smalish species, but so tasty.
I can tell you from experience my experience that they almost all have the long white worm looking parasites in the body cavity, if you are eating the guts you are probsbly chowing down on cooked worms.... If you care about that sort of thing
Don't know about the regs, but the molt usually occurs after a new or full moon I think. I also think it's highly dependent on how much the animal is eating and how big it is species etc.
I've always wondered if you had a lobster that freshly molted if you could whole fry it. I tried the standard baking and its a PITA because the meat sticks to the new soft shell and doesn't pull free like in a hard shell version.
As for that worm, Jeremy I bet it's a parasite but I haven't seen the one you described. There's a gnarly fat one that grows under the "tail" of deepwater crabs, it's some sort of barnacle and looks like a fat worm.