Here is the script wich creates a new post, here you can put stuff per default in the posts.
Look at add_post.php in /modules/news/
around line 42
// Insert new row into database
$database->query("INSERT INTO ".TABLE_PREFIX."mod_news_posts (section_id,page_id,position,commenting,active) VALUES ('$section_id','$page_id','$position','$commenting','1')");
Prior to these lines you can set variables holding default data and by adapting the query you can insert them easaly.
Note, since this is a core file, ALL news pages are affected and an update would undo your editing.Have fun!
John