If I configure bitwarden to generate long passwords, what happens if that exceeds the maximum password length for that site?
If I configure bitwarden to use all possible characters when generating a password to use for a particular website, what happens if that site disallows certain characters in passwords?
If I configure bitwarden to use limited characters (i.e. a passphrase) to generate passwords, what happens if the site requires upper, lower, digit, and punctuation?
Does Bitwarden know the specific password rules of most websites to avoid the issues in my above questions?
Short answer: no. There is no accepted/adopted standard for websites to communicate their password rules to password managers, and Bitwarden does not maintain a database of such rules. So if a Bitwarden-generated password does not meet the password rules for a site, all that will happen is that the website will give you an error message indicating that the password was rejected.
You just have to try again if your first attempt fails. One helpful feature in Bitwarden is the password history, which lets you view and copy previous passwords for each login item. Thus, if you saved a new password in Bitwarden before determining that this password did not meet the password rules for the site you are on, it is easy to go back and retrieve your old password.