Why does Bismillah Not appear at the beginning of Surah Taubah and Why is There Repetition?

Q: Why does Bismillah not appear at the beginning of Surah
Taubah?

A: When Hadhrat Uthman  (Radi’Allahu Anhu)  was asked why there was no bismillah at the beginning of Surah Taubah in the manner that there is bismillah at the beginning of other surahs, he replied that there was some doubt as to this surah being a separate surah, because Nabi
صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَم passed away without explicitly mentioning anything regarding it.
This is why Bismillah was not written at the beginning of Surah Taubah. However, since its subject matter is similar to that of Surah Anfaal, it was placed after it and a space for Bismillah has been kept because it is possible that this is a separate surah. (Tirmizi, Vol 2, Pg.139)

In Bukhaari Shareef (Vol 2, Pg 271) it is mentioned that this surah was revealed to cancel the peace treaty. In it appears the command of killing the mushrikeen (polytheists) and the expression of Allah Ta`ala’s anger over them. Therefore, Bismillah was not written at the beginning of the surah since Bismillah signifies peace and mercy.
It appears in Shaatbi: Bismillah does not appear at the beginning of this surah, because it was revealed in connection to war.

This is not the actual reason though it is a point to consider. The actual reason is that which is narrated from Hadhrat Uthman 
(Bayaan-ul-Qur’aan, Vol 4, Pg 95)

Why is there repetition in the Qur’aan?
Q: What is the wisdom in the repetition of certain topics in the Qur’aan?
A: What is the wisdom of certain words being repeated in your speech?

This person remained silent.
Hadhrat then said, “You are asking the wisdom of the repetition in Allah Ta`ala’s speech whereas you cannot explain the wisdom of repeating your own words? This repetition does not decrease the level of eloquence. Similar aayaat (verses) may appear in other
places and in every verse something different is intended.
Another reason may be as Moulana Aashiq Ilaahi
 has written in the footnote of his translation of the Qur’aan under the verse:

(O jinn and man! Which of your Rabb’s (Lord’s) bounties do you deny?) [55: 13]

This verse appears 31 times in Surah Ar-Rahmaan. Moulana writes that there are many types of the bounties of Allah Ta`ala and each verse refers to a different bounty.

Malfoozaat of Faqeeh-ul-Ummat Rahmatullah Alaih