bismillah

What should a masbooq recite when standing up for missed rakaats?

Q:

1. Suppose I am offering Asar or Maghrib and I joined the Namaz in the last Rakaat after missing the first three rakats, now when the prayer ends with "Assalaamu alaikum warahmatullah" by Imam and I get up from "Attahiyyaat", Then what do I have to say first? Do I have to start my next rakat with thana or bismillah?

2. Also, do I have to say a surat after reciting surah fatiha?

Why does the Qur'an start with Bismillah?

Q: My question is very basic and very few of us would have actually noticed it. Although we Muslims recite it most frequently. Firstly every verse of the holy Qur'an starts with bismillah, meaning "In the name of Allah". Secondly we all consider the Qur'an to be preserved in its original form and not a single word has been added or deleted by Prophet Muhammad (Sallallahu Alayhi Wasallam). Thirdly we all know that the source of the Qur'an is Allah Ta'ala himself. My question is why Allah would start the Qur'an saying "In the name of Allah" if Allah himself has revealed the Qur'an. Every verse of the Quran must have started as "in my name" and not as "in the name of Allah". Can it be possible that Prophet Muhammad (Sallallahu Alayhi Wasallam) himself added bismillah keeping in view the first aayah "iqra"?