Yes, you can have a direct link.  New versions of a file uploaded to Repository will replace old versions and continue to use the same URL.

This thread explains the download options for Repository:
 
  http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/54/threadid/281085/scope/posts/Default.aspx

Cheers!
-mamlin

Replacing [FILE] with [URLCONTROLFILE] in the form.html template file will result in a DotNetNuke URLControl being used for uploads, so in addition to being able to upload a new file, you can also select an existing file on your server, or enter a URL. You do not have to upload a file using the File Manager, you can still upload a file directly from within the Repository module.

You can always directly link to a Repository file , you just need to know the URL.  If you are using the [URLCONTROLFILE] token in your form.html template file, then the DNN URLControl will write the file to wherever you put it and he URL will be easy to use.  If you use the [FILE] token, then you will be using the Repository upload control which mangles the filename by inserting a GUID between the filename and the extension. This prevents overwriting files of the same name and provides a little security by making the URL impossible to 'guess'.  If you upload a file using the [FILE] token, you'll need to use the File Maager (or FTP client, etc) to look in the folder to determine what the actual filename is. You can then construct the direct URL to the file.