Corruption of scriptures

I have asked this question of many Muslims and have yet to get a logically consistent answer: Does the Quran say, or does it not, that the Bible has been corrupted? If so, in which verses is this found? A typical answer I have received when I ask is that "Allah only promised to protect the Quran. He never said he would guard the Bible too."

Yes. And?

If it is really true that no one can change the words of Allah, and that He sent down the Tawrat and Injil beforehand, uncorrupted, then how can Muslims contend that the Quran is the only perfectly preserved scripture just because it's the final one? Why would Allah fail to guard the previous scriptures if the Quran merely confirmed them? Or is it that the Quran does not confirm the earlier scriptures at all but instead contradicts them?

I can already hear a Muslim's answer to the last few questions: DO NOT QUESTION ALLAH.

Here you may find an argument that I have yet to see refuted. The gist:
Claims (verbatim):

The Quran is preserved.

God’s Revelations which preceded the Quran include the Torah, the Psalms, and the Gospel.
These Books make up a large portion of the Holy Bible.

The Quran, the Torah, the Psalms, and the Gospel are all the Word of Allah.

God's Word does not change.

The revelations that came before the Quran have become corrupted.

Although Muslims should believe that these previous Books are the genuine Revelations from God, they have to trust only the Quran as the final revelation and the only one that is preserved.

Those claims result in these premises, a dilemma for Muslims (verbatim):

1. The Quran, the Torah, the Psalms and the Gospel are all Allah’s Word.
2. The current Torah, Psalms and Gospel are corrupted.
3. The final word of Allah, the Quran is preserved.

1st Conclusion: Some of Allah’s Words are corrupted
2nd Conclusion: Some of Allah’s Words are preserved.

Read the rest for yourself, then comment and answer the questions I originally asked.

A few questions

Just to start out with, here are a few of my pressing questions for you (the rest of the blog will be about this too, but why not have a unique post about it?):

• Why is the Quran organized by sura length and not in chronological order? It seems to me that it would be much easier to understand if what was revealed first was written down first. After all, is Allah a god of order, or not?
• Since the Quran says, "O ye who believe! Ask not questions about things which if made plain to you, may cause you trouble. But if ye ask about things when the Quran is being revealed, they will be made plain to you, God will forgive those: for God is oft-forgiving, most Merciful.. Some people before you did ask such questions, and on that account lost their faith." (Sura 5:101-102), should I even be asking questions about Islam? If truth really does stand out clear from error, shouldn't questions strengthen one's faith? (I am not saying I am a Muslim. I am just asking the question.)
• Since the New Testament (by this I mean the four accounts of the life of Jesus Christ, the books on the early history of the Church, and the canonical epistles) came after the Old Testament (the Torah and the Prophets), we ought to judge it by what came before. In this way, Christians find out whether their God is being consistent and faithful or not. By similar logic (time alone), we should judge the Quran, revealed after the Old and New Testaments, by what came before. Indeed, the Quran itself exhorts us to do so. Indeed, even in fields like biology and geology, the past ought to be the key to the present. So, my question is, why is one supposed to judge the Bible by the Quran?