I do back up my wallets, but that's just me copying wallet.dat and moving it somewhere else.
Only octocoin addresses I've used is the one to receive from pools and one for faucets way back when. In other coins' wallets, I can see specific addresses in "send" and "receive" sections. The Octo wallet just has a "request for payment" form when I click on the receive button.
If you want to see all of the addresses that have been used as receiving addresses in your OctoCoin wallet: Click on "File" then go down to "receiving addresses" and it will show a list of all addresses that have received coins in that wallet.Solo mining will also create new receiving addresses in your wallet, too... sometimes a new one for every block found.So here's my test transaction from last week sent to the burn address.

Is "Input" the address I should be listing in the google form?
If you have had transactions received by more than one address, then there will be different addresses as inputs, even if you send them all at once. I had wallets on a couple of different computers and each had multiple addresses and I sent them all to a newly created address and used that address on the form and to send my coins to the burn address.
Your best bet, to insure you get credit for all of your coins is to: 1. Create a new address... 2. Send all of your coins to that address... 3. Use that address on the Google form for the burn.