I'm looking to get into retouching/post-production work... Maybe you guys can help

First of all, what is it really called, as a job description? Or, a more fitting title for it (so if I were to be... googling it for instance, I would get the most relevant results).

Second, can anyone in this field/related fields suggest places/ways to improve upon this area of work? I'm not terribly interested in taking a course for it, so other resources would be most helpful. Are there stock sites that I can use to practice, and better yet, to build my portfolio from? Is Photoshop the primary tool for editing?

Third, as you can see, I'm a manipulator (of images, that is, *grins*), how relevant is a background in manip to doing retouching? Any tips?

Any help in this would be AWESOME. Really getting tired of my office job...