"Is there a way to edit the file information (description) without updating your file (update suggests newer version)?"
You do not need to change the file at all, if you do not want to. Click the badly named link "update file" (Should be named "update submission"), and then do not click on the "change file" link. That answers your question exactly. And if you do not want to increment the version number then do not increment the version number: this is not automatic, nor is it required.
You can change the just the description, just the file, just the image, or whatever combination of these you wish to perform. Note that any change will be listed in the "updates" list at the bottom of the page. But "update" does not mean that the file has changed!
