What does the Imam say after prolonging his sitting in the first Tashahhud? And how should the finger be moved when reciting the Tashahhud, and what is the ruling on one who does not move his finger?

It is sunnah for the Imam and for one praying alone, upon completing the first tashahhud, to stand for the third rak'ah without saying anything. As for moving the finger during the tashahhud, there are details regarding it mentioned in previous fatwas.