Password Life Expectancy_

Because you should never type a real password into any website, including this one. There is no password field here at all. You describe the shape of a password using switches and sliders, and the tool does the arithmetic on that description, so there is nothing sensitive to leak in the first place.

Entropy measures how many guesses an attacker would have to make. Each extra bit doubles that number, so 40 bits is a thousand times harder than 30 bits. It depends on how the password was chosen rather than how complicated it looks, which is why a long random passphrase beats a short jumble of symbols.

Because the speed of an attack depends almost entirely on how the site stored your password. A rate-limited login form allows perhaps a hundred guesses a second. A leaked database hashed with bcrypt allows a few thousand. A leaked database hashed with an obsolete fast algorithm allows trillions. The same password can be unbreakable in one case and gone in seconds in another.

Almost not at all. Cracking software applies those substitutions automatically as standard transformation rules, so replacing letters with lookalike symbols adds only a bit or two of real strength while making the password much harder for you to remember. Length is worth far more than cleverness.

Usually yes. Four genuinely random words carry more entropy than eight random characters, and they are far easier to remember. The important word is random, because a phrase you composed yourself from a favourite lyric or saying is guessable in a way that dice or a password manager are not.

No. There is nothing to store, because you never enter a password. The whole calculation runs in your browser from the switch positions alone, and nothing is transmitted anywhere.