Well, I do not see this set of icons at the bottom of the text area.
First of all, your start page (revest) shows the discussion plugin, which has it own internal text area and its own editor. That is neither the Dokuwiki editor nor the ckgedit editor.
Secondly, if I go to
http://wiki.revestou.fr/doku.php?id=revest&do=edit, I see the standard ckgedit toolbar and screen. If had write permission, then I would be able to login, enter text and save it.
As for the IFrame plugin, had you read the ckgedit documentation, which is extensive, you would have known that ckgedit supports only the subset of CKEdit functions that is compatible with Dokuwiki, except for the font styles. For the syntax you must look at the Dokuwiki syntax specification which is included with the Dokuwiki distribution.
As far as I can see ckgedit has installed correctly and if there are any other problems they would be a result of either your template or how it has been installed or of the browser you are using.