Well, with used (D)SLR's, shutter count is something you need to know, because it depends on if that camera has much more life left in it or not, and cameras don't come with a shutter count in the menu. You have to take it to a camera shop or have some computer app or something to find it out, because it is in the camera, you just have to dig to get it out. But like with any electronics, for me, I like to buy new. Get the warranty, get the latest tech, take care of it and don't buy anyone else's problems.
And I have Adobe Photoshop CS5, and the book on how to use it, and my son's help from him having an Assoc Degree in Graphic Design, and that's what they used in school. Been using it for a good 15 years probably. Couldn't live without it. Couple of things it does like under "Image," then "Adjustments," then "Shadows/Highlights"... that's one of the best, handiest, most awesome little photo edits I've ever seen, and I use it quite a bit, especially for ebay images.