>> How does this handle situations where the generated password isn't accepted by the site? eg. Is too long, absolutely must have at least one symbol and one number, etc.

You can specify password length if it gets too long and it's character set provides symbols, numbers and letters in it.

>> How does this handle changing passwords?

It has a renewal mechanism to switch to a new password.

>> How can I know from the master secret that xyz.com is on the 4th password?

Can you explain more about what you mean?