By default I know that OS X does not allow you to do any modifications from inside the open dialog, like
- rename files
- move files
- delete files
- tag files/folders
Is it possible to tune the system in order to enable this functionality?
Why not do all this in Finder? Check this animation for a useful way to locate your file in Finder, directly from any Document window and Open/Save dialog:
I use this dozens of times every day.
The Default Folder X add-on could help you out here. It offers a ton of additional features for the Open/Save dialog including favorites, file/folder renaming and deletion and access to metadata (tagging).