And WD-40 can be sprayed on your fishing lures also. There was a big deal around here with the walleye fishermen, in particular, of spraying it on and I guess it leaves a scent trail or something.
By the way, people will tell you that it has silicones in it that cause fisheye if you try to paint over it. There was a big deal on the board about a year ago about this. I took a piece of wood and literally soaked it in WD-40 then painted it with spray poly. If there was any recipe for fisheye, and WD-40 caused it, that would be it. No fisheye.
As far as the crayon, yes, we only used it on painted drywall. And we sometimes went back over it with Simple Green or 409 then blotted to get the oil stain out faster. Our kids never wrote on fabric or papered walls, much preferring to remove the vinyl from the papered kitchen walls, so I can't speak from experience on that.