Thank you for submitting homework task-2 in Crypto-Academy.

If you are going to use then you should know the real importance of these three keys. By these keys you can access to the wallet, if you lose them you also loses your account. No keys let you no access to account.
Now days some cases also happened to many steemains they lost their tron account keys so they lost their tron

You can restore your wallet using any of the three forms of private keys-- Private Key, Mnemonic Key, Keystore File. So you should keep them safe, preferably off-line.

Further, if you are going to restore your wallet using Private Key/Mnemonic Key then you don't need a password, rather you can reset the password and set up your wallet in a new device/fresh installation. But if you are using the Keystore file to restore your account, then you need the password(set by you in the previous installation) too.

Keystore File+Password(set by you) ~ Private Key

Thank you.