Is a random PW more secure than a memorable PW for the same length?

RickCunn

This https://blog.1password.com/how-long-should-my-passwords-be/ will give you good insight. See especially the section regarding entropy.

Of course you will need to never forget your master password. But it is also critical the remember your device passwords, and your iCloud / Apple account passwords.

Use the Emergency Kit to handle the former, and perhaps also write down the latter as well, keeping them in a secure location.

Some of us share vaults and / or these credentials with others, so that they become addition points of access.