Demons 101 Ghosts, Ghouls and Wraiths Shapeshifters Angels, Sirens and Unicorns oh my! Vampires - How the Native Vampires Suck Compared to Me! Vampires - From a Human's Perspective Witches - The Good, The Bad and The Ugly Why We Don't Make Deals. Creatures That Want to Eat You
At least, those are the ones they make you take before you can go out on hunts, I think. The combat ones are kind of optional, but I've actually been helping with one of them.
I don't know a lot about the tattoos, but if you talk to Sam or Dean Winchester, they can tell you more.