2
Once an article is submitted, it can be approved like so:
1. Enter admin menu
2. Go to "News" -> "Post / Edit News"
3. Click on title of article to approve.
4. At the bottom of the Edit Article form there is a drop-down that reads "Preview", change it to "Save"
5. Click "Go!"
You will be able to modify this article using the same form.
Not exactly sure what you mean by "Big Story" but perhaps the Spotlight module is what you are looking for:
http://modules.xoops2.com/modules/mydownloads/singlefile.php?cid=1&lid=1