Good description. On the design of kunai as well, Shurikens actually have more of an aerodynamic design, but we will get to that later. However, kunais are meant for one per hand, and can be used for close range combat. The reverse grip is a nice touch, and you are correct, I also see Kakashi do this a lot in the manga. Furthermore, by releasing a full wave of kunais at someone, it distracts their vision of sight, as they will be focused on what is before them. Within a battle, it is important to know where your opponents focus will be. By using flashy moves, you can get them to stare upon that only while you cook up another move that can flank them from the back. Naturally, by using this jutsu, their attention would be focused on the kunais, so keep this in mind the next time you battle. It is a good distraction, so use it to the best of your ability.
Now, what do you know of Shurikens?