That's one of the main reasons I had to get a PSP was to play Crisis Core, because it focused on Zack. He's a pretty easy-going guy in CC but he's fiercely loyal.

As for the puppy comment, I'm pretty sure Zack's mentor Angeal called him as such- just because he was quite excitable, but after certain events the pup grew up into a wolf who would do anything for those he accepted into his personal pack.

I think both for letter E fit Zack, practically to a T.

If you ever get the chance, I would suggest trying out Crisis Core. ^.^