Rainbow, about the Quranists, this is really controversial. You say, they return to the Quran alone. This makes them non-muslims, because Muslims need to follow the prophet Mohammed.
All of this presumes that the hadith are accurate records of Muhammad's words and deeds. But how could they be? They were compiled about 250 years after he died. We all know how quickly stories mutate and words get distorted. Imagine what could happen in 250 years!
But more importantly, as you pointed out, much of the hadith directly contradicts the Qur'an. The Qur'an is supposed to be the word of God, while the hadith are only the words of a man named Muhammad (maybe). If one conflicts with the other, which should a true Muslim obey? If a muslim chooses to disobey God and follow a man instead, then how can he call himself a Muslim?
Muhammad himself once uttered some 'satanic verses' which acknowledged the existence of "Allah's" daughter goddesses Al-Lat, Al-Uzza and Manat. Should Muslims become polytheists? In one hadith (I can't recall where) he catches some other muslims recording his words on parchment and forces them to burn the parchment, telling them that the Qur'an is all they need.
The entire orthodox sunni position contradicts itself. They claim to be strict monotheists, but they worship a man who has been dead for over 1400 years. Yet another way in which they are just like the Christians.