The thing is that the ahadith(the sunnah) are the explanations for our actions. Like how to pray, how many rak'at etc. So these narrations that you posted up are in accordance to the law of Allah, they are sahih and they have been agreed upon by the ulama in the action there in(kiilling the one who exits the religion), as it was the practice of the Prophet Muhammad and the khulufa arashedeen. Aside from that some verse that point to the fact that murtad has done something great and is deserving of a punishment that I found in some of the books of fiqh are verses 38-39 of surah anfal.. Say to those who have disbelieved, if they cease (from disbelief) their past will be forgiven. But if they return (thereto), then the examples of those (punished) before them have already preceded (as a warning). And fight them until there is no more Fitnah (disbelief and polytheism: i.e. worshipping others besides Allah) and the religion (worship) will all be for Allah Alone [in the whole of the world]. But if they cease (worshipping others besides Allah), then certainly, Allah is All-Seer of what they do. Please keep in mind that the ayat that you posted are according to a person who was a kafir not who became a kafir after excepting Islam. Sometimes due to our limited knowledge we cannot come to a conclusion on a hadith that says something, and another hadith says something else(possibly even the opposite), However the fact is that our problem is not in the ahadith or ayat but rather it is our understanding. The prophet alayi salaam said I was ordered to kill the people until they say La ilaha Illa Allah..... But we also know that there is no compulsion in religion.... So how do we reconcile? We have to go to the scholars, and we have to understand each of these statements according to the true and real meaning, and we have to look at the sunnah, and ahadith, and actions of the sahaba, and the statements of the ulama to see how to implement these things in the right way.. If we can't then we believe in the ayat, and ahadith(according to its authenticity) without understanding how or why, until Allah gives us tawfeeq in understanding them. and allah knows best...