I'd definitely go with the 'Hello Kitty' stationary. The 'Hello Kitty' boxerbriefs went over so well in Ohio last year.
As far as character sheets go (and remember that all my opinions should start with the phrase 'How the hell should I know?') Do whatever communicates the character and your familarity with him or her. As long as the page gives some idea of the character and his general attitude, you're set.
For example, let's say you've got a frenetic wild character. His character sheet should have lots of poses showing him from all sides. Maybe the character is shadow boxing or leaping around and over the body copy on the page, smashing a block of type at the bottom right corner.
Or you've got, say, a sour old bastard character. He might only have two poses on the page. One cranky face-on pose, and one pose where's he's walking away from the reader, head turned totally away and hand waving dismissively. The background might even be black and sullen with white type reversed out, or maybe in thought balloons.
I dunno. Does this sound sensible?