Whoever catches up with the imam when he is bowing, and bows with him, that is regarded as a rak`ah for him, according to the view of the majority of scholars, even if he did not recite al-Fatihah.

There is nothing wrong with reading du’a al-qunut from a piece of paper or a booklet in Witr prayer until one is able to memorize it. It is not obligatory for the du’a of Qunut to be in the words narrated from the Prophet.