Surah

This narration in Bukhari came from Uriah ibn al-Zubair narrating from his aunt Ayisha Bint Abi Bakr. Many of great Ulama from Shia and Sunni schools refute this narration and openly say that it is a fabricated narration aiming to hide the reality behind the incident of poisoning the Prophet Muhammad (SAWA).

The Quranic verses 69:44-47 were wrongly translated by a translator who does not know Arabic properly. Arabic word (Lao لو) does not mean simple (If) but it is used for the impossible only. حرف امتناع لامتناع . Same (Lao لو) came in Quran to prove that there no God with Allah and if there was a god with Allah, the whole skies and earth would have spoiled لو كان فيهما آلهة إلا الله لفسدتا

This (Lao لو) is used for the impossible.

You will see that the Prophet (SAWA) never changed nor claimed anything from himself.

Wassalam.

Predestination is everything in life which is out of our will or control like our creation, our birth place,v our family,our skin color, or height, our eyes color , our body functioning etc. every predestined matter is never part of our our responsibility. Our faith and deeds are our responsibility and every one with be questioned about his faith and deeds. Allah (ASWT) Says in Quran :And stop them, verily they will be questioned. Sura Saffar, verse 24.

Sura 65:3 says that everything created by Allah has a discipline and order. It never says that our deeds are destined or I forced in us. Allah Says in Quran ( We Have guided him ( human being) the way, and he decides to be grateful of disgraceful) Sura Al-Insaan, verse 3.

Wassalam.

1. This verse (6:159) means something completely different from what seems from your question. شيعا means different groups following different leaders, which is totally different from the word Shi’a which means the followers of the Prophets and their real successors.

2. Shi’a in Arabic language means the followers, who can be followers of true leader, so they are the real believers, or can be following a wrong leader, then they will be mislead.

3. Allah (SWT) Has Granted the title Shi’a to His best servants as you can read in Sura Al-Saffaat after mentioning the Prophet Noah, the mention of Prophet Ebrahim ( And Ebrahim was from his Shi’a) (وإنَّ مِن شِيعَتِهِ لَإبراهيم. 
4. Allah (SWT) mentioned in Sura Al-Qassass about Prophet Musa and his followers and his enemies. He called the followers of Musa as his Shi’a and the opposite people as his enemies. Al-Qassass, verse 15.

'5. Shi'a is a title granted by Allah, The Glorious, to the sincere followers of the Prophets.

6. Shi'a Muslims are the real followers of the Prophet Muhammad (SAWA) through following his Progeny Ahlul Bayt (AS) which was been ordered by Allah and the Prophet (SAWA).

7. The Prophet Muhammad (SAWA) has repeatedly called the most sincere believers as "Shi'a of Ali" as you can read in many Sunni books of Hadeeth like

1. Shawaahid Al-Tanzeel by Al-Haakim Al-Hasakaani , V. 2,  P. 356. 
2. Kufa Ayat Al-Talib by Al-Kanji Al-Shafi'ee, P.244.

3. Al-Manaaqib by Al-Khawarizmi Al-Hanafi , P. 62.

4. Al-Fosoul Al-Muhimmah by Ibn Al-Sabbagh Al-Maliki , P. 126

5. Ibn Asaakir in Tareekh Dimishq 2:442.

6. Al-Khateeb Al-Baghdadi in Tareekh Baghdad, V.12, P. 289.

7. Al-Tabarani in Al-Mo'jam Al-Waseet, V. 6, P. 354.

'Wassalam.

The verse you mentioned reads ( And we did not send any messenger but in the language of his people to state clearly for them, and Allah leaves to astray those whom He like and guides whom He Wills. And He is The Exalted, The Wise.).

All the previous prophets and messengers were been sent in the language of their people. The last messenger were sent in the Arabic language which can be easily translated and understood by all human beings.

'Wassalam.

Sura Al-Hamd is the most important Sura in Quran which is called Ummul Kitab which means the mother of the Book.

'Sura Al-Tawheed is one third ofvthecQuran.

'Sura Al-Kaafiroon is one quarter of the whole Quran.

'You should study whatever you can from the Quranic verses.

Wassalam.

Yes of course. Carrying Quranic verses or Suras can protect us from evil and harms.

Wassalam.

The reward depends on the intention in your heart and the concentration in your mind. Allah Knows all the languages and He Grants great reward to the sincere believers who duplicate or recite Quran with dedication and humbleness.

Wassalam.

There are many supplications and Quranic verses to be recited in this regard like repeating Istighfaar, repeating Salawaat,v reciting Sura Yaseen and reciting Sura Falaq and Sura Annaas.

Wassalam.

Bismillah ARRAHMAN Arraheem is part of every Sura in Quran except Sura Al-Tawbah. Leaving Bismillah ARRAHMAN Arraheem ( deliberately) will invalidate the Prayer.

'Bismillah ARRAHMAN Arraheem is the Greatest Verse in Quran.

Wassalam.