I think it was moiii CC: this is adorable! question for you. do you take your illustrator lines into photoshop after they're lined? If sooo. how do you prevent it from going huge? and how do you make it appear with separate layers? ;o;
No, I don't do that. The only thing I use Photoshop for is the initial sketch, as it has brush controls that Illustrator doesn't. I use (in almost all cases with a couple exceptions, like this: [link]) Illustrator for the line work and colors. I specifically use the Live Paint tool to color it.
As far as bringing Illustrator vectors into photoshop... well, I don't know quite what you mean by huge. I'm guessing there's a problem with the resolution of your Ill. image and your new Photoshop document. You need to make sure the image size and resolution is where you want it whenever you start a new document. These are all done on 3"x3" documents with 300dpi resolution. I could do it at 72dpi, really, as it's for the web.
You can't, as far as I know, import an entire Ill. document into Photoshop and preserve the Ill. doc's layers. It will automatically flatten it. You can, however, export each layer in Ill. as a .PNG, files that have a transparent background, and import each one into Photoshop. They'll each be on their own layers.