Can you store these after you open the can? If so for how long?

The container says to use them within 3 weeks of opening, I stored them in a plastic container in the fridge and a month later there were some white spots forming on them, which looked off. Maybe it's normal, but it's best to use these quickly rather than storing them.

Sorry to belabor for the buyers…seller, is this NaCl? health requires i know my chemistry bc not all salt is safe.

NaCl is sodium chloride. Basic table salt. I'm very careful about the ingredients as well.

Is the flavor of the fresh peppercorn very briney?

If you rinse the peppercorns with water before adding them to the recipe, the briny flavor will be tempered. However, the heat of the peppercorns will remain.

What color is the brine

the brine is clear with green tinge that is due to the color of the green peppercorns. it contains only salt and water, according to the contents list.