new Mac user-iPhoto and iTunes questions

I recently switched to a 2013 Macbook Air 13" from a Microsoft Surface after being a lifetime Windows user. I've got a couple of questions with how these two programs handle their file structures.

Do iPhoto and iTunes "copy" your pictures and music folders already in place, therefore leaving 2 of the same libraries on your hard drive? One for Finder use, and the other for i____?

I'm not quite wrapping my head around this structure as in Windows, Media Monkey and Picasa would simply monitor my folders for changes, not create their own library. I have the 256GB hard drive on my Mac and would hate to see my pictures and music take up twice the necessary hard drive space (though I have a 1TB external hard drive as well). I am trying to make the full switch to Apple in some instances, and making sure I know the pros and cons. I've defaulted to Picasa on my Mac, but find it a little cumbersome and nearly impossible to upload pictures to Facebook for my wife.

Thanks for any help!