Sebastien,
I don't think any of this is crazy.
The first idea is similar to the HTML composition GUIs which now seem to be everywhere. I'm told it's a pretty complex task to get them to reliably be both WYSISYG and to maintain syntactically correct markup through multiple edits, but people are attempting it---with some success for HTML and BBcode.
Could org-syntax be used in a Wiki? I suppose so with some elisp or scripting infrasturcture. In fact, such an idea is has potential to help with other problems as well, such as making simple changes to your server-stored org-documents when at a non-emacs machine or a simple web-enabled device like a smartphone. I imagine that the overhead of processing org-markup to html via Emacs is high-ish in comparision with traditonal ways of generating html from other markup languages. But with static pages and mostly internal use, that should be no issue.
Look at this link for an example of online PDF generation. In this case it's from another lightweight markup language called ReStructured Text, and uses pdflatex on a server to automatically generate pdf's.
http://rst2a.com/
If they can do it.....
Scot