Is it part of every Suurah?

Bismillaahir rahmaanir rahiim is written before every Suurah [with the exception of Suurah at-Tawbah]. The scholars disagree if it is from the Qur'aan in this place.

It is not a part of the Qur'aan. It is written only to derive blessing from it. This is the Madhhab of Maalik and a group from among the Hanafi. It is an opinion among the Hanaabilah.

It is either a Verse or a portion of a Verse from every Suurah. This is the Madhhab of al-Shaafi'i.

It is from the Qur'aan where it is written as a Verse from the Book of Allaah at the beginning of every Suurah but is not a part of the Suurah. This is the Madhhab of Ibn Mubaraak, Ahamd, and others.

Reference(s):

Majmuu' al-fataawaa
Volume 22 Page 438-439