How often should I backup my wallet, and where should I save the wallet.dat file?
You don’t need to back up your wallet, as long as you have your private keys backed up. Just make sure your wallet is encrypted with a STRONG password.
Backing up your private keys in a safe place will ensure you can always access your funds even if you lose your wallet file. But if your wallet file is not encrypted, someone with the ability to copy it will be able to extract the funds from it.
Dump private keys + store them safely. Encrypt wallet. 2 simple steps.
Don't mind my signature, there's probably more important info in the text above it.