A.
For action number 6, I am told to enter "listaddressgroupings" to get a list of my public adress. Doing so will give me a long list of all addresses I have previously used for transactions. Am I correct in assuming that using any of these addresses (and only that one) in action number 6 will give me the private key I need to have a paper wallet (and reach my goal of what I want to achieve (mentioned at the top of this text) ? Or do I need to repeat action 6 for every Bitcoin address I have received Bitcoins to (even if all Bitcoins are in the same Bitcoin-QT wallet) ?
You will need to use
dumpprivkey for every single address that you have ever used. That command only returns the private key for one address, so it does not apply to any other address in your wallet.
If you are using a wallet made in Bitcoin Core 0.13.0, you can use
dumpwallet and open the output file and get the master private key. Since Bitcoin Core 0.13.0 uses deterministic wallets, all you will need is the master private key.
B.
What is the corresponding actions that I need to take to "start over" if my computer and all USB-backups are destroyed? This is my guess:
- Download and install Bitcoin-QT to a new computer
- Action 1-5 above
- importprivkey [my private key from my paper wallet] (any parameters?)
- Anything else?
For importprivkey, you will want to do
importprivkey <key> "" false. This will import your key into the default account (well hopefully accounting will be removed by the time you import so this won't matter) and it will not rescan. The very last key you import you will want to set that false to true so that it rescans the blockchain.
C.
Someone wrote that if I do a "backup of wallet to paper" procedure of my Bitcoin-QT wallet (action 1-7 above) the paper wallet becomes useless if any transactions are sent/received from my Bitcoin-QT wallet? How can that be?
Even if I continue send and receive transactions from/to my Bitcoin-QT wallet should not the paper wallet work just as fine if I need to start over (as described in question "B" above)?
It depends. If you are using a wallet created in Bitcoin Core 0.13.0+, with the master private key, it doesn't matter. You can still send and receive.
However, if you use a wallet created in an older version, it does. This is because when you send and receive you are constantly generating new addresses. If you receive Bitcoin, you should be giving the sender a new address. If you are sending, you will produce change which will go to a new address. These new addresses is randomly generated so you won't have a backup of them.
