You might have to wait longer before seeing anything poolside, I have some miners that take 30 minutes before they start mining as they have to do all this optimisation crap on each board. Admittedly I don't have an Avalon but it may be they do that too.
Also I assume you are using
YOUR actual BTC address and not the example address from the ckpool website which is: 1PKN98VN2z5gwSGZvGKS2bj8aADZBkyhkZ
And lastly, no there is no place for a secondary or backup pool in the Avalon GUI which is a PITA if you ask me.
Also you have to reboot the miner after every change
From the manual:
Note: After pressing the save key,please remember to restart the machine to make sure your
mining pool configuration effective. To restart it, users can click Reboot on the left, or press
RESET key (on the miner) or restart the miner physically.