Hadith

Yes. This Hadeeth of Ghadeer has been narrated by biggest number of companions who witnessed it and heard it from the Prophet Muhammad (SAWA). It is more than Mutawatir in Sunni books as well as Shia books.

1. Sibt ibn al-Jawazi said in his book Tathkirat al Khawas  (Pg 30 & 31) "All the Ulama of Sirah have unanimously said that the incident of Ghadeer took place when the Prophet (SAWA) returned from Hajjatul Wida when he said in front of 120000 companions : Of whomsoever I am the Maula Ali is the Maula. The full Hadeeth mentions that the Prophet (SAWA) started his sermon "Allah is my Maula and I am the Maula of all Mo'meneen". Then he said am I not more entitled on the Mo'meneen than themselves upon themselves? All said "Yes". He (the Prophet SAWA) : For whomsoever I am his Maula, this Ali is his Maula.

2. Abu Ishaq al Tha'labi mentioned in his Tafseer that when this announcement was spread in different places a man by the name of al Harth ibn al No'man al Fahri came to the Masjid of the Prophet (SAWA) and objected on the announcement of Ghadeer and asked the Prophet (SAWA) : Is it from you or from Allah SWT? The Prophet (SAWA) became angry and his eyes became red and he said : By Allah SWT who is La Ilaha Illahu it his from Allah SWT and not from me.

3. In this Sahih Muslim (Vol 7, Pg 122 & 123) a Hadeeth narrated by Zaid ibn Arqam that the Prophet (SAWA) said in Ghadeer Khum : I am leaving among you two important things ; the first the Book and Allah SWT and my Ahlul Bayt (AS). 

4. Ibn Hajar said : Hadeeth al Ghadeer is definitely authentic and there is no doubt about it. 

5. An Nasai in al Khasa'is narrated from Zaid bin Arqam Hadeeth al-Ghadeer (Pg 39).

6. It was also narrated by al-Mohib al-Tabari in Thakha'ir al-Oqba.

7. Also in ibn al-Maghazili in al-Manaqib (Pg 29).

8. Also al-Muttaqi-al-Hindi in Kanz al-Ommaal (Vol 1 ; Pg 166)

9. Also al-Qurtubi in his Tafseer (Vol 18 ; Pg 287)

10, Also al-Haakim-al-Hasakani in Shawahid-al-Tanzeel (Vol 1 Pg 158)

Many other Sunni books have narrated Hadeeth al-Ghadee with the frase of Allah is my Mawla and I am Mawla of all believers and forwhom soever I am the Mawla, Ali is his Mawla.

Wassalam.

Hadeeth Kisa is one of the most  authentic Hadeeths in both Sunni and Shia books. It was narrated by more than twenty authentic narrators like Umm Salamah, Abu Sa'eed Al-Khudri, Ayisha, Jabir ibn Abdillah Al-Ansari and others. Sunni and Shia books narrated Hadeeth Kisa in its brief version stating that the Prophet Muhammad (SAWA) called Ali, Fatima, Hasan and Husain and put on them a cloak (Kisa') and said: O Allah, these are my Ahlul Bayt. He did not allow any of his wives to join them despite the request from Umm Salamah and Ayisha in two different occasions when the same happened in their presence.

Beside this narration, there is another long narration of Hadeeth e Kisaa' by Jaabir ibn Abdillah Al-Ansaari from Fatima (AS) which is been recited by the followers of Ahlul Bayt (AS) in their religious and social gatherings for getting the blessings. This narration of Hadeeth e Kisaa has been narrated  by many great scholars with full chain of authentic narrators. In 'Awaalim of Shaikh Abdullah Al-Bahrani from Sayyed Hashim Al-Bahrani, from Sayyed Maajid Al-Bahrani, from Shaikh Hasan ibn Zain Al Abidin (Al-Shaheed the Thani), from Al-Muqaddas Al-Ardabili, from ibn Abd Al-AALI Al-Karaki, from Ali ibn Hilal Al-Jazaeri, from Ahmad ibn Fahad Al-Hilli, from Ali ibn Al-Khaazin Al-Haeri, from Ali ibn Al-Shaheed Al-Awwal, from Al-Shaheed Al-Awwal, from Fakhr Al-Muhaqqiqeen, from his father  Hasan ibn Yousuf Al-Allama Hal-Hilli from Ibn Nama Al-Hilli, from Muhammad ibn Idrees Al-Hilli, from ibn Hamza Al-Toosi, from Muhammad ibn Shahr Aashoub, from Al-Tabrasi of al-Ehtijaj, from his Shaikh Al-Hasan ibn Muhammad ibn Al-Hasan Al-Toosi, from his father Al-Shaikh Al-Toosi from his shaikh Al-Mufeed, from his Shaikh ibn Qawlawayh, from his shaikh Al-Kulaini, from Ali ibn Ibrahim, from Ibrahim ibn Hashim, from Ahmad ibn Muhammad ibn Abi Nasr Al-- Bizanti, from Qasim ibn Yahya Al-Jallaa', from Abi Nassar, from Aban ibn Taghlib, from Jabir ibn Yazeed Al-Jo'fi, from Jabir ibn Abdillah Al-Ansari from Fatima (AS).

Many other great scholars have also narrated this Hadeeth like Fakhr Al-Deen Al-Turaihi in his book Al-Mubtakhab Al-Kabeer, Al-Dailami  of al-Irshad in his book Al-Ghurar WAL-Dorar. Al-Husain Al-. Al-Hanafi who is a Sunni Hanafi Aalim has also narrated this Hadeeth.

Wassalam.

Writing Hadeeth was officially banned during the governments of Abu Bakr and Umar and Uthman and Bani Omayyah till the time of Umar ibn Abdul Zeez which was on years 99 till 102 after Hijra when he allowed writing Hadeeths and ordered one of Shaikhs working for the Umayyad government ( Ibn Shihab al-Zohri) to write Hadeeths which are accepted by the government that time.

Mussannaf Abdul Razzaq, Mawatta' Malik, al-Imamah wal-Siyasah are among the early books.

Wassalam.

We don't have such narration suggesting the Prophet Muhammad (SAWA) is from the tribe David. David is from Ishaq (AS) while Prophet Muhammad is from Ismael (AS).

You need to ask the person who claims that to provide authentic evidence supporting his claim.

Wassalam.

This Prophetic Hadeeth (Ali in this Ummah is like the Ka'bah) has been narrated in both Shia and Sunni books including:

1. al-Soyooti in his book Thail Al-La'aali , page 62.

2. Tareekh Dimishq by Ibn Asaakir Al-Shafi'ee, V. 42, Page 356 .

3. Al-Manaaqib by Ibn Al-Maghaazili , page 107 and 149.

4. Kifayat Al-Taalib, page 161.

5. al-Manaaqub by ibn Shahrashoob , v.3, page 202.

6. Osd Al-Ghaabah by Ibn Al-Atheer, V. 4, P. 106.

7. al-Manaawi in his book Konooz Al-Haqaa'eq , page 203.

8. Al-Qondoozi Al-Hanafi in Yanabee' Al-Mawaddah, page 182.

and many other Sunni and Shia books.

The Hadeeth means among many important points that people should come to Ali for guidance and following him, and he should never go to any one for guidance or following.

Worshiping Allah in obligatory Prayers is only accepted when you face the Ka'bah, and obeying Allah is only accepted when you follow Ali as the appointed divine leader after the Prophet by order of Allah (SAWA).

Wassalam.

There is a full field of knowledge called E'lm Al-Rijaal which deals with every narrator and searching and assessing his authenticity. Deviat persons are known by our scholars of E'lm Al-Rijaal and their narrations are never accepted.

Famous  Shia books on E'lm Al-Rijaal are like Kitab Al-Rijaal  by Al-Najaashi (450 Hijri),

Rijaal Al-Kashshi (350 Hijri) ,

and  Al-Fahrist by Al-Shaikh Al-Tousi  (460 Hijri) , 

Ma'aalim Al-Ulama' by Ibn Sharashoob 588 hijri.

Khulasat Al Awwal by Al-Allama Al-Hilli  726 hujri.

Tanqeeh Al-Maqaal by Al-Mamaqani 1351 hujri.

and Mu'jam Rijaal Al-Hadeeth by Al-Khoei 1413 hijri.

We only accept narrations from authentic narrators who were always in the right path.

Wassalam.

It is not our job to determine who will enter Paradise or who will not. Allah knows the intentions and circumstances of every creature, and He grants Paradise to whom He wants, according to His Knowledge and Mercy.

No doubt, the authentic Hadeeth is mentioned in both Sunni books and Shia books states that: Who dies with out giving allegiance to the Imam of his time will die a death of Jahilyyah. ( Musnad Ahmad bin Hanbal, v,13, p. 188 and Saheeh Muslim, v.6, p.22 and Kitab Al-Sunnah by ibn Abi Aasim;489 and many other books of Hadeeth.

Wassalam.

The Hadeeth stating that who dies without allegiance to the Imam of his time, will die the death of Jahiliyyah (Ignorance) is a Mutawaatir Hadeeth which means narrated by many authentic narrators that can never jointly lie. 
It has been narrated in many Sunni references like:

1. Musnad Ahmad Ibn Hanbal, V. 28, P. 88.

2. Saheeh Muslim, V. 3, P. 1478.

3. Hilyatul Awliyaa' by al-Asbahani, V.3, P. 244.

4. Kitab Al-Sunnah by Ibn Abi 'Aasim , V.2, P.503.

5. Al-Sunan Al-Khubra by al-Bayhaqi, V.8, P. 270.

6. Saheeh ibn Hibbaan, V.10, P.434.

7. Sunan Abi Dawood, V.3, P.425.

8. Al-Mo'jam Al-Kabeer by al-Tabaraani, V.19, P.334. And many other Sunni books.
Main Shia books as well narrated this Hadeeth like:

Kitab Al-Kaafi by al-Kulaini 2; 21,

Kamaal Al-Deen by Al-Sadouq;2;409,

and Kifayat Al-Athar by Al-Khazzaz 296.

Wassalam.