There is no re birth but resurrections or return to this life which known as Raj'ah رجعة.
Raj'ah is the return of best servants of Allah and worst enemies of Allah to this life again to witness the victory of Islam and the punishment of its enemies. It is mentioned in Quran ( Sura Ghaafir, verse 11).
Imam Hussain (AS) will come back to this life in Raj'ah.
Shawaahid Al-Tanzeel by al-Hasakaani شواهد التنزيل للحسكاني is well known book containing many Hadeeths fron Sunni sources in favor of Imam Ali (AS).
Main changes in Salaah were done during the rule of Omar ibn Al-Khattab. There are hundreds of narrations even in Sunni books about these changes initiated by Omar. You can see Al-Nass WAL-Ijtihad by Allama Sharafuddin and also Kitab Al-Waa'il which is a Sunni book by Abu 'Oroobah, stating who initiated what among Muslims.
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.
It has been very clearly mentioned in many authentic narrations from our Infallible Imams e.g. Imam Ja'far Al-Sadiq (AS) that: My Hadeeth is the Hadeeth of my father, and it is the Hadeeth of my grand father, which is the Hadeeth of Imam Husain, which is the Hadeeth of Imam Hasan, which is the Hadeeth of Ameerul Mo'mineen, which is the Hadeeth of the Prophet (SAWA) which is the order of Allah.
(Kitab Al-Kaafi, V.1, P. 53.).
In the Shi'i view, it is held that the knowledge of the Prophet (S) passed directly to the Imams. Therefore, when one of the Imams speaks, they are speaking accurately and correctly on behalf of the Prophet, whether or not it is word for word.
In some cases, the Imam may have a dialogue with someone present with them, refer to people in their time by name, or discuss current events and questions. In these cases, these are not word for word quotations from the Prophet (S) but accurately reflect or expound upon the Prophet's teachings as applied to those situations.
In other cases the Imams provide a direct quotation from one of their forebears.
Apart from that, it would be very lengthy to always give the full chain of narration back to the Prophet (S) through all the Imams. However, it is understood that this is intended to be the chain of transmission of knowledge.
This principle is mentioned in al-Kafi and is related from Imam al-Sadiq (A) as follows:
"My hadith is the hadith of my father. The hadith of my father is the hadith of my grandfather. The hadith of my grandfather is the hadith of al-Husayn. The hadith of al-Husayn is the hadith of al-Hasan. The hadith of al-Hasan is the hadith of the Commander of the Faithful. The hadith of the Commander of the Faithful is the hadtih of the Messenger of God (peace and blessings be upon him and his family). The hadith of the Messenger of God is the word of God, the Mighty and Glorious."
علي بن محمد، عن سهل بن زياد، عن أحمد بن محمد، عن عمر بن عبد العزيز عن هشام بن سالم وحماد بن عثمان وغيره قالوا: سمعنا أبا عبد الله عليه السلام يقول: حديثي حديث أبي، وحديث أبي حديث جدي، وحديث جدي حديث الحسين، وحديث الحسين حديث الحسن، وحديث الحسن حديث أمير المؤمنين عليه السلام وحديث أمير المؤمنين حديث رسول الله صلى الله عليه وآله وحديث رسول الله قول الله عز وجل.
Here, of course, the "word of God" does not mean the same thing as the Qur'an being the "word of God" in the sense of the literal divine word, but rather is the correct teaching given from God to the Prophet (S).
So, from a Shi'i perspective, the Imam has full knowledge of the teachings of the Prophet (S) and full authority to speak about it. Therefore the Imam can speak authoritatively without giving a further chain of narration back or may provide a further chain of narration back.
Hope that helps!
We can not say that every vocal melody is disallowed because the way of Tajweed, Azaan , Nawhakhwani etc has a vocal melody. The music which is usually used by the sinners is not permissible even if it used in Noha or Tajweed.
If the melody is used by the sinners, then we must avoid it.
We have narrations in Mustadrak al-Wasaa'il (2:484) from the Prophet (SAWA) that the spirits of the believers come back on Fridays near their homes and every one from them will call him family members who are alive: O my family, O my children, O my father, O my mother, O my relatives; have a sympathy on me, may Allah have sympathy on you....
أرواح المؤمنين ليلة الجمعة
2525 / 24 وقال (صلى الله عليه وآله): " ان أرواح المؤمنين تأتي كل جمعة إلى السماء الدنيا بحذاء دورهم وبيوتهم ينادي كل واحد منهم بصوت حزين باكين: يا أهلي، ويا ولدي، ويا أبي، ويا أمي وأقربائي اعطفوا علينا يرحمكم الله بالذي كان في أيدينا والويل والحساب علينا والمنفعة لغيرنا وينادي كل واحد منهم إلى أقربائه: اعطفوا علينا بدرهم أو برغيف أو بكسوة يكسوكم الله من لباس الجنة "، ثم بكى النبي (صلى الله عليه وآله) وبكينا معه، فلم يستطع النبي (صلى الله عليه وآله) أن يتكلم من كثرة بكائه، ثم قال: " أولئك إخوانكم في الدين، فصاروا ترابا رميما، بعد السرور والنعيم فينادون بالويل والثبور على أنفسهم يقولون: يا ويلنا لو أنفقنا ما كان في أيدينا في طاعة الله ورضائه ما كنا نحتاج إليكم فيرجعون بحسرة وندامة، وينادون: أسرعوا صدقة الأموات ".
مستدرك الوسائل-ج٢ ص ٤٨٤
We have in our main books of Hadeeth two narrations from Esma'eel son of Imam Ja'far Al-Sadiq (AS); one in Al-Kaafi by Al-Kulaini , volume 7, page 388, and the second narration is in Al-Tahtheeb by Al-Shaikh Al-Tousi, volume 6, page 287. The reason can be because he passed away during the life of his father when people used to take the Hadeeths from Imam Ja'far Al-Sadiq (AS) himself.
I did not find any narration in our main books from Muhammad ibn Esma'eel who was in touch with the Abbasid tyrant Haroon Al-Rasheed who put imam Musa A;-Kadhim (AS) in jail for long years then killed him by poison.
Dajjal ( The Deceiver) is one of the definite sign of the Reappearance of Imam al-Mahdi (a) along with the Heavenly Cry, the riot of Sufyani, and the riot of Yamaani. There are narrations that Dajjal will be killed by Imam Al-Mahdi (AS).
According to a narration by Al-Shaykh al-Saduq from the Prophet (SAWA), mention of Dajjal has been in the past but his presence will be in future.
According to Hadiths, Dajjal appears at a time of hardship and starvation, deceives a group of people, and gathers them around himself.
Qutb al-Din al-Rawandi narrated a Hadith from the Prophet (SAWA) through Sunni sources saying, "No prophet was ever assigned to mission unless he alarmed his people about the mischief of Dajjal."
The authentic Hadeeth in al-Kaafi encourages kissing the hands of the Prophet (SAWA) and his Holy Progeny and any one whose hands are kissed for the sake of them. No doubt, kissing the hands of your parents is very good and also the hands of pious scholars who are servants of Ahlul Bayt (AS) and the hands of any believer as far as this kissing his hand is for the sake of Allah and not for worldly matter.
We have narrations like this however some scholars do ta'wil of these narrations and state that if kissing someone's hand such as a righteous scholar, is done with the intention of glorifying Ahlul Bayt (as), then it is permitted. This is because many respect the righteous scholars due to them being those who spread Ahlul Bayt's (as) teachings, and there narrations from the imams (as) themselves emphasising on respecting the righteous ulema as well as keeping away from the evil ones.
May Allah grant you success