Imamah

Not all of the names you mentioned in your question had really claimed Imamate,but it is a fact that some of the children or grandchildren of curtain imams did wrongly claim Imamate.The reasons behind that were mostly political and for gaining worldly benefits. All those who wrongly claimed Imamate had failed,despite the political and financial support from the rulers and governments of their times who were always interested and keen to create dispute between the followers of Ahlulbayt. Being a son or a grandson of the Infallible Imam does not mean that he is also an Infallible,we read in Quran how one of the sons of prophet Adam [AS] did kill his own brother. Al-madeena [5]. We also read in Quran about the son of prophet Noah who disobeyed Allah and his father.Hud[45]. It is worth mentioning that most of those sons of grand sons who did wrong have repented their mistakes.

wasalam.

We believe that Allah The Exalted does not have a physical shape and He is not limited to a place. Allah SWT said in Quran about Himself  ''LAYSA KA MITHLIHI SHAY'E'' Surah 42 Ayah 11, which means nothing at all is similar to Allah SWT. Allah SWT does not have any objective existence, but he is everywhere, and he mentioned that the most humble of his servants hear on His behalf, and they serve Him and implement His orders. '' Ears'' of Allah SWT are those most pious servants who hear on behalf of Allah. ''Eyes'' of Allah SWT are the most humble servants who Seefor the sake of Allah SWT. ''Hands'' of Allah SWT are those most humble servants who implement the orders of Allah SWT using their hands for the sake of Allah. So there is no Literal meaning in these words at all, but these words should be understood as part of understanding the Arabic language, which uses the words as can be understood as the the literal word.

Wassalam 

Yes. There are Quranic verses as well authentic Hadeeths.

'Quranic verses mentioned the similarity between Prophet Muhammad (SAWA) and Prophet Musa (AS) (Verily, We Have Sent to you a Messenger (Muhammad) , who will witness on you, as We sent Musa to Pharaoh as a Messenger) (Sura Al-Muzzammil, verse 15. The successors of Musa were twelve as we read in a Quran (Sura Al-A'raaf, verse 160). These two verses show that as Musa (As) had twelve successors, Muhammad (SAWA) will have twelve successors.

'Authentic Hadeeths narrated in Shia and Sunni books including Bukhari, Muslim , Tirmithi, Musnad Ahmad Bin Hanbal, Mustadrak of Al-Haakim and many others mentioned that the successors after the Prophet Muhammad (SAWA) will be twelve .

'Wassalam.

The Prophet Muhammad (SAWA) did mention the names of all the twelve Imams (AS) as the real successors of the Prophet who will lead and guide the whole world as the Prophet was leading and guiding. As Allah (SWT) Has ordered us to obey Him, the Prophet and our divine leaders, Infallibility is necessary for them otherwise how can we obey Allah in obeying a person who can commit sins, which leads us to sinning which is against the obedience of Allah.

'Every infallible Imam has clearly mentioned who will be the Imam after him, which keeps the whole chain of Imams fully authentic and all of them are infallible.

'Wassalam.

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.

The Prophet (SAWA) and the Infallible Imams (AS) who have been martyred are alive and never dead. Allah says in Quran ( Never say dead to those who were been killed in the way of Allah, in fact they are alive but you don’t feel. (Sura Al-Baqara, verse 154).

All Muslims greet the Prophet (SAWA) in every Prayer by saying: ASSALAMU Alayka Ayyuhan Nabiyyu Warahmatullah Wabarakatuh. Which means that the Prophet is alive that is why we greet him from where ever we are.

'The Prophet and Infallible Imams listen to us and pray for us.

'Wassalam.

The number of the twelve Imams is mentioned in Quran when mentioning the divine leaders after Prophet Musa (Sura Al-Maa'idah , verse 12).

Allah (SWT) Mentioned that Prophet Muhammad is sent to people as Prophet Musa was sent. (Sura Al-Muzzammil , verse 15.

'From these two Quranic verses we know that the divine successors of the Proohet Muhammad are twelve just like the divine successors after Musa.

'Mentioning the names of the twelve Imams explicitly is not our job to ask as Allah did not mention explicitly the numbers of units of our most compulsory daily prayers and left if to the Prophet (SAWA) to explain. Allah Knows what to mention and not.

'As the Prophet Muhammad (SAWA) mentioned the number and the names of the twelve Imams, every Muslim must believe and follow the Prophet (SAWA).

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.

Allah (SWT) Has ordered us in Quran : O you who believe , Obey Allah and obey the Messenger and your divine leaders. Sura 4, verse 59.

'This verse is very clear that it is obligatory to obey Allah absolutely and always, and to obey the Messenger absolutely and always and the divine leaders absolutely and always. This means that all their orders are according to Allah and the Messenger Hesse it is obligatory to obey them as we are ordered to obey Allah and the Messenger. This means that these divine leaders are fully pure and never commit any sin otherwise if they possibly commit any sin then Allah will never Order us to obey a person who might commit a sin as such order can lead to commit a sin which is impossible.

'Sura 33, verse 33 is also clear that Ahlul Bayt are fully purified from any sin or error.

'With out the fact of the infallibility of Ahlul Bayt (Aas) it will be possible to follow any sinful act of the leaders. This is impossible to order Muslims to obey a sinner. Allah says in Quran: : My promised authority will never reach to sinners. Sura Baqara, verse 124, which is very clear that divine leaders can never be sinners.

Wassalam.