Hi, I'm back and I need a little help with getting started.

1) I found my first legendary pet, Esteban, and I want to know what makes legendary pets special besides the fact that they are legendary. Are they just better than the normal ones or something?
2) Is there a CS in the first town? I can't seem to find one.
3)Can someone sum up the pet system in a few words? I don't really understand it.
I guess I kinda need a guide for the game since its been so long since I've played an mmo.