|Making it an administrative share would not allow regular users to access the drive, only members of the administrators group (or domain admins etc).|
As far as I know, you should just be able to share the CD like you would a drive and then map to it.
Is there a disk in the drive? If not, that could be why you get the "device not ready" message when attempting to connect to it.
As for making changes to group policies. If you dont' remember which changes you made (this is why we document, so we don't have to remember everything we do, you might want to consider doing some documentation of your own) you'll pretty much have to go through the entire policies to find the settings you need and make changes to them.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.