Re: Background image for text area in wiki
Yes, that's div class="wikitext", and you can assign a background image to it by editing your stylesheet. (One example: http://themes.tikiwiki.org/Business.) Either modify the theme stylesheet that you're using, or add "custom.css" to the directory in /styles of the theme you're using (e.g., styles/strasa/custom.css), with just the div.wikitext {background: ....} rule.
-- Gary