OK, lets go through the suggestions:
Anime: Used picture by cal
Manga: Used
this.
Comics: No change to this point. Please suggest a specific picture to use. Thanks.
Cartoons: Used pic suggested by cal, but due to cropping it to a square the writing is cut of, so maybe we should use another one.
Visual Novels: Used picture suggested by cal, but maybe we should use a picture with characters instead of just writing, since more appealing for a viewer
TV Series: Used
this since it was avaiable. If someone gives me a picture of supernatural I will replace it (the supernatural picture I found on their verse page didn't work since it wasn't approximately a square and just writing isn't very appealing in the first place)
Games: Used
this picture of Link.
Light Novels: No change, since To Aru seemed to be agreed on.
Books: Used Harry potter, with
this image.
Movies: Used Star Wars, with
this image.
Powers and abilities: Used picture on the energy manipulation page, as suggested.
With this we have left Terms, Important, Characters and weapons.
About the naming: Since the categories (except the characters category) lead to the verse pages, I would consider it unfitting to name them "Anime Characters" etc.
Just naming them "Anime", Manga", "Comicbooks" etc. might be a idea?