Yup, decapping removes the shell. This both saves you from dealing with separating the shells from the shrimp, and gives a somewhat higher hatch rate. It can be done on a small hobbyist scale by simply soaking the shrimp in FW for an hour, adding bleach to double the volume of the soak container, stir for about 5 minutes (till the eggs to change from brown to orangish in color), rinse really well and add to your hatch container
My eyes have a hard time seeing the color change. So I use one of those flexable desk lamps to shine light at the side of the container to see it better. You don't want to over bleach or they will not hatch.
Standard unscented bleach. I do a second cycle with vinegar to neutralize the bleach. You can also store de-capped eggs in a super saturated salt solution so that you don't have to de-cap each time you want to hatch.. Just dissolve salt (tank salt) in water (warm) until you can't possible get any more to dissolve...Drop your de-capped eggs in and refrigerate. (The super saturated salt water re-dehydrates the eggs) They will store for a couple months this way. Also, if you start buying eggs in "volume" you should store them in the fridge pre-decap/pre-hatch to extend the shelf life.
Yup, standard old unscented household bleach. Acid won't work to decap, other than as a weak rinse after the bleach to remove any residual bleach. Though in practice, I find simply rinsing them really well for a few minutes is sufficient...for small batches.