Why is there no system directory where a person might access all system utilities, like background, text size, color, etc. Must I download a separate utility for everything?
All appearance options are in the 'Appearance' section of the 'System Settings'.
There is also myunity in the software center that lets you modify the Unity interface.
Finally there is compizconfig-settings-manager , but this tool is very advanced, so I wouldn't recommend it to novice users.
Edit: To keep this answer up to date: There is now also Unity Tweak Tool which lets you change almost every part of Unity.