The Koran is a much smaller "scripture" than the Bible, so there is little sense in trying to compare them as you have. The Sunnah are not scriptures at all, but testimonies of supposed witnesses to Mohammed's actions. They have a whole "science" of determining which are more acceptable, and which are not. They have much the same problem with witness reliability as your local police do, too. There are certain sunnah accepted by different sects of Islam, some of which are not accepted by other sects.
survey says? XXX
The Koran is roughly the equivalent of the four cannonical Gospels of the New Testament, as established under the Council of Nicaea. The Koran is literally held to be the directly recited word of Allah, and cannot be interpreted, reworded, modified, even translated out of Arabic. Inconsistencies in the suriyah are explained by the cute little dodge that Allah can change his mind, replacing older and outmoded commandments with newer more perfect ones. Read the Koran - it's in there. The "later revelations" are SO much fun that way.
The Hadith of the Sunnah are the rough equivalent of the lesser books of the NT (Acts, Epistles, etc...) plus the non-canonnical Apocryphal Gospels and testaments. The Hadith are held to be accurate testimonies of the words of Muhammad and inspired by Allah. There is some wiggle room for interpretation, but not much. Nor is there much motivation for doing so, because "Allah hates those who ask too many questions" and the penalty for unrepentant apostasy is death.
Facts. Deal with them.