IIRC it's called a passphrase. It's a backup of your wallet that is encrypted. It means you can not use that to import your address in another wallet. If you want the accessible backup, export your privatekey and save it in a document or print a scannable version of it so you can import it in any allet which supports address importing.
No it isn't. It's a seed. You can use it in any other wallet that works similarly and the same addresses and coins will be in there. It's all you need to backup or move your coins wherever you want if it's BIP 39 or 44 like Trezor and a few others.