Imamah

Bukhari book known as Saheeh al-Bukhari has mentioned in its original editions Alaihis Salam for Ahlul Bayt in many places of his book. Same in many other Sunni books of Hadeeth like Musnad Ahmad ibn Hanbal, Ibn Abi Assim in Kitab Al-Sunnah, Ibn Battat in Kitab Al-Ebaanah  and Al-Lalakaei in Shah Osool Ahlul Sunnah.

Many promenant Sunni scholars like Shaikh Adnan Ebraheem of Palestine and many other Sunni scholars use Alaihi Assalam for Ahlul Bayt (AS).

'Wassalam.

Seeking help from the most humble servants of Allah who do everything by permission from Allah, is seeking help from Allah. We seek help from the Prophet (SAWA) and Imam Ali (AS) because of their greatest status with Allah, which makes their Du'a for us accepted rather than our direct Du'a because of our sins. Saying Ya Rasolallah or Ya Ali Madad is based on the firm faith that they are the best servants of Allah and their intercession helps us by permission of Allah.

Never listen to Wahabi false propaganda which claims that it is Shirk or polythemy.. They do not understand the real meaning of Tawheed as it is in Quran and authentic Hadeeths.

Wassalam.

Quranic verses are clear that the Prophet (SAWA) helps the believers and he is very sympathetic on them, and he is the source of blessings on the believers.

'The Infallible Imams are the real successors of the Prophet (SAWA) and did and still do the same to help the believers. They are in fact the keys to open the gates of mercy for the believers and we have many authentic narrations stating that.

'Wassalam.

Yes, The infallible Imam's were teaching their sincere followers to seek the vasilah of Ameerul Mo'mineen Ali (a.s). Wasalam 

The Prophet (SAWA) has clearly mentioned on many occasions that he will be succeeded by 12 Imams or 12 Leaders 12 Successors This has been narrated even in the Bukhari book and Muslim book and Musnad Ahmed Ibn Hambal book and many other books of Hadith.

The names of the 12 Imams were been mention also by the Prophet sawa in many Hadiths narrated from by Ahlul Bayt (AS) as well as hadiths is narrated by Sunni Scholars for Example Shaikh al Islam of his time Shaikh Suleman al Kunduzi who was the head Sunni Aalim of Hanafi Sects of Istanbul in his famous book Yanabi'ul Mawaddah has narrated with continuous chain of narrators the Prophets mentioning the  names of all the 12 Imams From Imam Ali a.s to Imam Hasan a.s to Imam Husain a.s to Imam Zainul Abedin as to Imam Mohammad Al Baqir a.s to Imam Jafar as Sadiq a.s to Imam Musa al Kadhim a.s to Imam Ali Redha  a.s to Imam Mohammad Al Jawad a.s to Imam Ali al Hadi a.s to Imam Hasan al Askari to Imam Al Mahdi atfs May Allah hasten his reappearance.

Another Hadith narrated in Yanabial Mawaddah of Al Kunduzi al Hanafi from Jabir Ibn Abdullah al Ansari saying that the Prophet saws told me that you will live long after me and you will meet the grant son of my grant son Husain a.s His name will be Mohammad Al Baqir a.s when you meet him convey my Salaams to him. This is also in sunni books.

Obviously, the enemies of Ahlulbayt a.s tried the best to omit such hadiths mentioning the names of 12 Imam a.s but still Allah swt had made some of the narrations remain in some of the Sunni books stating the names of the 12 Imams as
Wassalam.

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.