[Typo3] tt_news: creator of the news

[Claudio Strizzolo]

Hello everybody,
I'm trying to set up tt_news in order to avoid people which are 
authorized to post news (let's call them "news editors"), to 
modify/delete news posted by other "news editors".
Basically, the news structure in the page tree is something like:

(folder) News stuff
      (folder) News categories
      (folder) News

The News folder is where the news are actually stored.
The whole structure is owned by admin, group news_editor: in this way, 
however, any news editor may modify news posted by other editors, which 
is what I'd like to avoid.
Other information: we have a great number of potential "editors" (over 
200), and they should all be allowed to post in any news category, but 
not to touch news posted by other people.
Any hints?
If the problem can be solved, then another thing I'd like is to avoid 
editors to set an "author" field while posting the news: I'd prefer that 
an identificator for the real creator is displayed, in the "list" and 
"single" news pages.
Again, any hints?
Thanks in advance

Claudio