If you only read the AIOWiki project, no more information is collected than is typically collected in server logs by web sites in general.
If you contribute to the AIOWiki project, you are publishing every word you post publicly. If you write something, assume that it will be retained forever. This includes articles, user pages and talk pages.
Deletion of content
Removing text from the AIOWiki project does not permanently delete it. In normal articles, anyone can look at a previous version and see what was there. If an article is "deleted", any user with "administrator" access on the wiki, can see what was deleted. Information can be permanently deleted by those people with access to the servers, but there is no guarantee this will happen except in response to legal action.