If you cant connect with the gnome tool to the cups server and the webinterface is not working, i guess your cups server is not running at all or has not been started.
Please all check the settings in /etc/cups/cupsd.conf
Did you get an error message when you execute this command on the shell:
Also, how does one make the printer show up in Samba aside from running 'cupsaddsmb -a'?
There are no other steps. But if cups is not running at all, the printers wont show up in samba.