wa'alaykumus salaam,
I am a student of Ilm-al-Kalam and the Mutakallimeen (rationalists). The four schools of Kalam are Jahmiyyah, Mu'tazilah, Ashariyyah, and Maturidiyya. The founding schools being the Jahmiyyah and Mu'tazilah - both of these schools of thought were Quran only Muslims; they did not accept the Ahadith and Sunnah as it was narrated by the followers of the Sunni Fuqaha (Jursits) and Muhaditheen (Scholars of Sunni Ahadith). Coming from this perspective, allow me to answer your questions.
Why would Allah mention the Messenger if we should only follow the Qur'an? <
Allah (swt) has mentioned many Messengers and Prophets, revelations and books etc. They served their purpose. His duty was but to deliver the message, to deliver the warning, and he (sa) did.
Allah tells us that His Beloved was the recipient so that he could expound it for us. Is this not the Sunnah? <
The reason why the Quran was separated from the Ahadith according to your sources was so that history and cultural traditions would not get mixed in with the religion, as was the case with the Jews and Christians, whose Bible consists of revelation - Taurat and Injeel, as well as history, perspectives of the authors, and rumored sayings of some of the Prophets. It was a mixture of revelation and ahadith - the Bible was. And that is why it is so untrustworthy today. If the Messenger of Allah (sa) said something at one point but Allah revealed something different to him later - as would be the spirit of the abrogation doctrine - then how do we know if one Hadith is valid for all times and generations? And what science of Ahadith are you depending on that only acknowledged people in a sanad as realiable because the followers of your Sunni Fuqaha trusted them?
When the Ahadith became separated from the ayats of Allah (swt), as instructed by the Messenger (sa) himself according to your sources, they now become susceptible to fabrication, unlike the Qur'an. Even the Muhaditheen admit that there were many fabrications and fabricators of Ahadith; likewise Sunni Muhaditheen did not accept narrators from Jahmiyyah, Mu'tazilah, Shi'a or Khawarij. The narration and collection of Ahadith is therefore biased as it accepts only those who the Sunni Muhaditheen (who were followers of Sunni Fuqaha) felt were trustworthy because they agreed with them theologically.
So Sunnah according to who? The followers of your Fuqaha? Your Muhaditheen? How is this fair?
The Messenger of Allah (sa) expounded as much as he needed to so that his companions and followers chould become content with the Deen and so that they could have some practical guidance in order to maintain some type of organization and discipline. This however was a seventh century man expounding to seventh century Arabs. There were contemporary and cultural implications to the thought processes of these individuals. They were limited in knowledge and understanding when it comes to fields of technology, science and philosophy as well. Thus the explanations were for them at that time, the Quran however is universal in its spiritual application.
What is this 'Hikmah' that the Beloved educates us with, in addition to the Qur'an? Is it not the Sunnah? <
No, it is Rationality - the Aql - or Mind. Hikmah or wisdom is something one arrives at when one uses the mind to reflect.
If the Prophetic guidance is restricted to the time of the sirah, how do you interpret his mercy for the universe and all existence? <
The consequences of Muhammad ibn Abdullah (sa)'s existence is the emergence, completion and perfection of the Deen. That by itself is a mercy.
Why is Allah referring to His Beloved as a a giver of glad tidings, and warner? Why not refer 'only' to the Qur'an? <
The Quran is a book. The Messenger of Allah (sa) is the one who Allah (swt) used to spread the message of that book. Thus he (sa) is appreciated for that, but not worshiped as a diety besides Allah (swt) by mimicking his every move - which is shirk. When you roll up your pants, sit and eat and bathe like him (sa) ... that is shirk in our eyes.
Why would Allah mention His Beloved being a good example to follow in such a general sense without it being relevant to all? <
He is no longer alive brother. He has passed away. He was a good example for the seventh century.
Some more questions
How do you pray? <
Personally, I still follow the sunnah as it is described by the Sunni/Shia. HOWEVER, I do not believe that the Sunni/Shia Salat is what the Qur'an intended Salat to be. To me, why is there even a question of 'how' to pray ... you should be able to pray in any position, however you want to pray to Allah (swt) without any ritual attached to your prayer. The only thing the Qur'an describes in full detail is how to do wudhu - and ablution is actually something commendable. But to go up and down and up and down talking in a language that is neither personal to me nor do I speak it, does not make any sense, nor does the Qur'an suggest for us to do it. Sometimes I pray in sajood only. I recite Sura al-Fatiha often. There are three times a day that I pray, as instructed to me by the Qur'an. My prayer does not have to be the formal Sunni/Shia Salat. Salat is not limited to the Sunnah. Even according to Sunni/Shia Ahadith the Prophet (sa) allegedly did different body gestures and said different things during the Salat. According to an authentic Hadith, a Muslim during the Salat being lead by the Prophet (sa) said Hamdan katheeran Toyaban Mubarakan feeh when the Prophet (sa) stood up from ra'koo. The Prophet (sa) said thousands of angels descended upon that man. This shows that the Salat was not limited. I've learned the Arabic, but I purposely pray in my own language. I don't need to follow Najdi Islam.
How many times do you pray?
Three times a day.
How many rakat do you pray?
No such things as rakats. This is from the Sunnah not the Quran. If I choose to follow the Sunni/Shia Salat, I will do the prescribed rakats according to their books.
When do you pray?
Fajr, Asr, Isha'
How much do we give for zakat and how often do we spend it?
Whatever one can rationally give. It does not matter how little or how much. One has to do it from the heart.
How do you do Hajj? What are the rites?
The Kabaa is not even mentioned in the Quran, nor is the black stone. We believe that those who stone a devil statue, kiss the black stone, run between the mountains and circle the Kabaa are unintentionally doing shirk. The pilgrimage has nothing to do with rituals and everything to do with the State of the Ummah address.
Can we consume alcohol? How do we know the chronology of the ayat on the topic?
For medicinal purposes, not necessarily for intoxication, unless the intoxication is supposed to be therapeutic for an illness.
What do you say of the Sahifah of Hammam b. Munabbih? He was a student of Abu Hurayrah and the manuscript dates to his time.
Who is this Father of the Cats you mention? How many years did he know the Prophet (sa)?
Why weren't the early Muslims 'Qur'an ONLY?' The Sahabah, including 'Umar, narrated hadith once they were sure the Qur'an was firmly established among the people. The followed Prophetic teachings in addition to the Qur'an and passed these on the following generations. Why isn't there a Qur'an only group with an unbroken chain back to the Prophet? Why has it only emerged in the wake on colonialism? <
The Early Muslims were. Before the Four Sunni Fuqaha and Muhaditheen ever started narrating and collecting their Ahadith, the Mu'tazilah and Jahmiyyah who were Muslims from the second and third generations of Islam (as-Salaf) never followed any Ahadith or Sunnah. Not only that but the Prophet (sa) forbade his followers from documenting any Hadith and told them only to write down the Quran - this is according to your Ahadith.
Ma'a salaama,
Farhan