Forum:Licenses of logo, background, favicon

Hi! I've got two questions about a few files from this site, which are used in polish version of Indiana Jones Wiki. I'm talking about files: File:Wiki.png, File:Wiki-wordmark.png, File:Wiki-background and File:Favicon.ico. I'm tidying up polish IJW and I would like to describe these files correctly. Could you help me? Obywatel Odbiór! 17:29, September 21, 2013 (UTC)
 * 1) Who is the author of these files? Did users of IJW make it, or only upload?
 * 2) What kind of license should I use to describe them? Can I use Creative Commons 3.0?