Actually tornado ... most products that are labeled kosher can only be kosher if it is prepared in accordance with Jewish law.
You are right in stating that Kosher salt has big crystals with large surface areas. But usually, it won't have any additives (iodine, for example). This size and shape allows it to absorb more moisture than other forms of salt, and this makes kosher salt excellent for curing meats.
That is essentially where the name comes from. The salt itself is not kosher, meaning it doesn't conform to Jewish food laws, but this salt is used to make meat kosher.
The Jewish holy book, the Torah, prohibits consumption of any blood, which is why kosher meat must be slaughtered and prepared in a specific manner. A common way of removing the final traces of blood from meat is to soak and salt it.
