Speaking of backing up the wallet, should you only back it up and keep the latest copy, or can you back it up again and again at different points in time? I guess I'm wondering if it's like a snapshot or not.
This works a bit different from that perception we have of files.
As we just saw, our wallet stores private keys (addresses) and we have to remember that there is a blockchain (where all the transactions are stored), the blockchain is stored across all the OKCash network nodes hence is decentralized and always available.
So. If you create a backup of your wallet when it has only 3 addresses, you could consider that backup valid and all your coins safe no matter when on time, as long as you dont create another address, as that backup only has 3 saved, so if you create more addresses then you would require to make a new backup, so you really have a full backup of all of your private keys (addresses).
As the Blockchain or in this case OKChain stores the transactions, as long as you have your private keys, the coins in those addresses are safe. So if you lose your hard drive with 600 coins in it, as long as your backup holds the private key for that address, you will have the full balance, no matter if someone send you more coins to that address and you had the computer off, you would still have the 600 coins and the new ones people send you as the transactions are stored on the Chain so are never lost, and as you hold the keys for your address, then only you can access them..