What do I need to log in with every time?

Just your email and password, the same as any normal site. There's a "Remember me" checkbox so you don't have to type it in every day if you're on your own machine, and a "Forgot password?" link that sorts you out if your brain decides to empty itself at the worst possible moment. If you ever need to change the password deliberately, that's under Profile & Brand in the account settings — leave the password field empty there unless you actually want to set a new one.