Usul al-Kafi

Hearing the angles is not restricted for the prophets only but many persons were mentioned in Quran used to hear the angles like mother of Musa ( We inspired to mother of Musa that: Suckle him ) Sura Al-Qassass, verse 7. 
Mariam, the mother of Easa used to hear the angles (Sura 3m verse 42 and 45) but she was never a prophet. Sara, wife of Prophet Ebrahim was also hearing the angles as we read in Quran (Sura Hood, verse 69 to 73).

Even Sunni Muslims claim that Umar ibn Al-Khattab used to hear the angles. They called Umar ibn Al-Khattab by the name: Muhaddath Al-Ummah. Fadhaa'il Al-Sahabah, by Mohammad Hasan abdul-Ghaffar, V.4, page 6.

The 12 Unfallible Imams were granted by Allah great gifts and abilities to guide the Ummah to the right path after the Prophet Muhammad (SAWA).

Islam was completed before the departure of the Prophet from this life. Infallible Imams never added any thing but preserved the real teachings of Islam. Their status definitely higher than mother of Musa and mother of Easa and Sara wife of Ebrahim.who were hearing the angles.
Wassalam.

Same question should be put for Sunni books of Hadeeth. Thousands of narration were been fabricated by Sunni narrators for different reasons, so how Sunni Ulama identify the authentic? Our Shia scholars do thorough research on every narration and all its narrators. We don't accept but the narration which is according to Quran and authentic Hadeeth and which has been narrated by authentic narrators one after another. Our main books of Hadeeth have much more authentic Hadeeths that what our Sunni brothers have in their books of Hadeeth.

Wassalam.

Such narrations are not to be taken for granted and most of our great scholars did not follow it in their verdicts. It might be talking about a specific year and can not be taken for all the years.

‘Wassalam.

According to Hadeeths narrated from Ahlul Bayt (AS), Kursi of Allah is His Knowledge about Skies and earths and creatures which has got an outer existence, while Arsh is His Full Knowledge about everything, which is more inclusive than Kursi. There are degrees of Knowledge, in which Arsh is deeper, wider and more inclusive than Kursi, that is why we read in the Hadeeth that The Kursi is within The Arsh. In the Hadeeth from Imam Ja'far Al-Sadiq (AS): Everything created by Allah is in the Kursi except His Arsh because it is greater than be included in The Kursi.

Hadeeth of Hanan ibn Sadeer from Imam Al-Sadiq (AS) when he was asked about Arsh and Kursi, he replied: Both of them are great gates of the Unseen. Kursi is the outer gate of the Unseen and Arsh is the inner gate of the Unseen.

Kursi is limited to the skies, earth and what is between them while Arsh is unlimited.

In some narrations we read that The Kursi is the knowledge which Allah granted to His Prophets and messengers, while  The Arsh is The Knowledge  which no one knows but Allah.

Wassalam.

Many Shia books of Hadeeth are already translated including all-Kafi. Many books are under translation. You can check on www.shiasearch.org

Wassalam.

There is no book of Hadeeth compiled by Shia or Sunni scholars which is 100% and fully authentic in each and every narration. Al-Kafi is the most authentic book of Hadeeth among Shia scholars. Bukhari is claimed to be fully authentic by many Sunnis but it contains narrations which go against Quran and allegation against the Prophets. The authentic Hadeeths in Al-Kufi are more in number than all the total authentic Hadeeths in all the six books of Sunni Hadeeth الصحاح الستة. 
Number of unrepeated narrations in Saheeh al-Bukhari is 2602 and in Saheeh Muslim 4000, while the number of unrepeated narration mentioned in both Bukhari and Muslim is 2514 narrations.

Al-Kafi alone has 16199 narrations.

Wassalam.

Allama Mohammad Baqir al-Majlisi is a great scholar in the Hadeeth sciences and he compiled the well known collection of Hadeeth in his famous book Biharul Anwaar. He has written others books as well. His grading is according to his own research and Ejtihaad. Other scholars have their grading which can be like or different from his grading as all the Mujahid scholars are free in their research in the narrators and narrations.

Al-Kaafi book has the most authentic collection of narrations of Hadeeth but we don't say that every narration in al-Kaafi is equally authentic. The expert scholars have their right to study and verify every narration.

'Wassalam.

This narration is weak and not authentic because of its narrator (Jafar al-Khuza'ee) is unknown and never been authenticated by any of our Ulama. Al-Majlisi in Baharul Anwaar mentioned that this narration is weak.

Al-Kho'ee in Mo'jam Rijal al-Hadeeth stated that the narrator ( Jafar Al-Khzaa'ee is unknown.

'The authentic narrations in all Shia books and many Sunni books stated that this verse was revealed on the Day of Ghadeer. (Al-Kafi 1:289, and 1:198) 

Many Sunni scholars narrated authentic Hadeeths that this verse was revealed on the Day of Ghadeer e.g.

1.Al-Tabari in his book Al-Wilayah,

2, Ibn Oqdah.

3. Ibn Asaakir.

4. Ibn Mardawayh.

5. Al-Hafidh Abu Na'eem in his book (Maha Nazala Min al-Quran Fi Ali).

6. Al-Khateeb al-Baghdadi in Tareekh Baghdad 8:290 .

7.al-Hafidh al-Sijistani in his book al-Wikayah.

8. Al-Khawarizmi in al-Manaaqib:page 80.

9. al-Hamaweeni al-Hanafi in Faraa'id al-Simtayn  in chapter 12.

No scholar can turn his face away from many authentic narrations and take instead a single weak narration.

Wassalam 

Such narration is not authentic because all ethnic backgrounds are equal in Islam and the Prophet Muhammad (SAWA) and Infallible Imams have married women from deferent ethnic backgrounds.

Wassalam.