[Well this is interesting. After getting the Moogle to walk him through the functions of the communicator again and having his Meow Wow laugh at him for his troubles, he thinks Sora sees this post.]

Some healing magic or a potion will help. Didn't the Moogle give you a potion to start with?

[And a pause. Yeah, there are other questions he could answer here, though he does wonder why the Moogles didn't provide this information.]

And to answer the other questions, the friendly Dream Eaters are called Spirits. The hostile ones are Nightmares. The Spirits will work with you and help you fight off the Nightmares. There's not much more to them than that. I don't know why the Nightmares carry munny, but they also have potions and dream fragments sometimes too.