I read this hadees and I have a question.
Whoever has belief and firm conviction on Allah should not miss recitation of "Inna Arsalna Noohan ilaa Qaumeh" (i.e. Surah Nuh) because whoever recites Surah Nuh in his obligatory and recommended prayer, Allah would allow him to stay with the virtuous and approved persons of Allah and would award him three gardens of Paradise with his garden by His special favors. He would marry the reciter to two hundred Hoorul Ein and four thousand other women (Sawab al-A`amal, Page 163/164)
Then have we to recite Surah Nooh in Namaz after surah fatiha or we have to recite it after namaz or if we have to read it in namaz then can we hold a book to read it as we don't remember is orally?

It says to be recited in the prayer here and is no problem in holding the Qur'an in your hand when reciting namaz if you do have the Surah memorized