You're making a mistake that many un-educated in Islam make, which is confuse Hadith (which was often law of the land at the time) with actual Quranic verses. My guess is you pulled most of the above lines from some anti-Islamic site, since I am having difficulty confirming the translations and exact phrases.
In any case, on the example you mentioned about the killing of apostates (those who turn away Islam). Whilst that may have been, and in some Islamic countries still is the law, it is NOT what is written in the Quran itself. Law of the land exists to set about specific rules required for specific controls at whatever point in history. At the time Islam was expanding, a slightly sterner set of laws was required to ensure it's adequate growth.
When you are fighting a war to spread your religion, the last thing you want is to open the flood gates for possible problem areas. Allowing people to turn away from Islam in those days could have been extremely detrimental to Islams overall success. But it was something that was done at the time for the reasons discussed (not that I agree with them).
Again however, I have to highlight the fact that this is not what is written in the Qur'an. No where in the Qur'an does it say to kill or harm infidels, non-believers or apostates. Only that God disapproves of them. We (as individuals) however, are not given the task to deal the punishments, that is decided by the law of the land and by God himself on the day of judgement.
We are only allowed to have a Fatwa (an opinion) and nothing more.
Back to the Apostates thing. I'd just like to phrase this sentence from the Qur'an, that does indeed confirm that the killing of apostates is something that was linked to only law of the land and not ordained by the Qur'an itself.
"There is no compulsion in religion" 2:256
"Let him who will believe it and let him who will reject it" 18:29
"Those who believe then reject faith then believe (again) and (again) reject faith and go on in increasing unbelief, Allah will not forgive them nor guide them on the way." 4:137
Now tell me, why would the Quran suggest that one can denounce Islam multiple times? Simple, because the Quran itself does not permit the death of apostates (nor infidels), that again, is something that was set about by Hadith, which unfortunately is often confused with simple law of the land at the time.
And another point on infidels...
"Lo! Those who believe, and those who are Jews, and Christians, and Sabaeans - whoever believeth in Allah and the Last Day and doeth right - surely their reward is with their Lord, and there shall no fear come upon them neither shall they grieve." (2:62)
There is also another sentence in the Quran that says non-believers can enter paradise whilst a Muslim can still end up in Hell. I just don't have it off hand with me right now, I have a page cornered in my Quranic translation somewhere. I'm not saying the Quran looks fondly on non-believers, but how we deal with them is not expressed in the Quran. In-fact, murder of any kind is completely haram (disallowed). You certainly can't go around killing non-believers or apostates, and no where does it say you will be rewarded for that either. As I said before, Allah decides that on the day of judgement, not us laymen. I think you should try and get a new angle on Islam, since your current sources offer a very anti-Islamic exaggerated distortion of things. We shouldn't keep confusing the verses of the Quran itself, and boundaries of law (of the land) with Hadith.
.