Whichever screen he uses has got absolutely _nothing_ to do with the quality of the images.
When taking a screenshot you make a shot of the gfx card output, not of what the monitor displays.
And they're called pixels if that's what you mean.
Any image editing program is usable when editing pictures. Photoshop is by far the best, but you have to pay for it, there is however a 30 day trial which you can re-new quite easily.
Save it anywhere apart from MS Paint, however if you do save it in MS Paint make sure that its .bmp and not .jpg as the BMP retains the quality. Get GIMP if you want a picture editor, you can even try some edits yourself.