Add/Change posting data

[Replicant]

Sounds like an interesting project. I'm by far no expert but here's my initial thoughts on the subject.
Changing the data array in the ckeditor submission probably won't work. Until the submission takes place, there is no nodeid to associate your anonymous user data to. Take a look at /js/ckeditor-rollup-519.js. This is where the post submission occurs.
A script will be needed for the additional anonymous info submission via a frontend controller.
I'm thinking you will need to capture the response data to get the nodeid of the new post,
then use that data to insert the node info in your new anonymous table.
Then you will need to add conditionals in the display_contenttype_threadview_header template (I believe) to check your anonymous info table for the current nodeid.
You will also need to create an API extension to get the data from the anonymous table (probably cache it) so you can call that function from the templates.