You should burn the cue file, the img and ccd files will be used as well when you burn the cue file (unless there's something wrong with your cue file, you can open the cue file in notepad (or any other text editor) to see if the ccd and img files are properly named)
As for burning images under linux, I'm not entirely sure, but I think the programs that are listed under "GUI (cdrtools based)"
here should work. Again, I'm not entirely sure, you might want to wait for someone who regularly uses linux to answer that.
As for your last question, again I'm not sure, but I think it would be image disc, as data discs are usually burned in a way to work on a computer...