Those are all free graphics, but it doesn't technically say that you can use them commercially. But as the webmaster created most of them, and says they are free to use you probably can. I would contact the webmaster about commercial use, as there is no stated license, just in case. If nothing else, they'll know that they helped you out.
No I told you before. Its best if your going to use other people graphics to modify them to a point. Example change the color , add or subtrat something. Change it enough so it looks similar but not exact copy. Honestly I draw any graphics myself or my animator will do it.