Re: Literature
Patrick,
Just to answer some of the very interesting questions you ask.
There is certainly nothing offensive or stupid about your questions - any muslim would be pleased to answer them.
What precisely is the Quran? Basically the Quran is the literal word of God, as revealed to the Prophet Muhammad (peace be upon him) via the angel Gabriel. Naturally given that the Prophet was an arab the Quran was revealed in arabic. It is amazing that the text of the Quran is the same, word for word, punctuation mark for punctuation mark as it was 1400 years ago. This confirms the promise of God in the Quran to safeguard its contents.
There is only one Quran, unlike say the bible which is not extant in its original language. Essentially the Quran is untranslatable - as you point out any translation will be imperfect. That is why all translations differ. For this reason muslims only consider the Quran to in arabic, and any interpretation must be made of the original arabic. The Quran is considered the greatest work in the arabic language even by many non-muslims. Its style is uninimitable - indeed the Quran contains a challenge to this effect - that man should produce a verse like it if he is able. This challenge has remained unanswered for 1400 years.
Although muslims believe in the religious texts before them (e.g. the gospels of Jesus, the torah of Moses, the scrolls of Abraham etc.) they believe that they are not in their original form and have been corrupted.
The other main corpus which makes up the core of islam is the life sayings/teachings/example of the prophet Muhammad (peace be upon him). These are the Hadith. The method of preservation was one of eye-witness testimonies which have a chain of narration (or isnad). The 2 most well known books of Hadith are Bukhari and Muslim (named after the respective scholars who compiled them). Roughly speaking for a hadith to be considered authentic and worthy of inclusion in a book, it would have to have 2 independent chains of narration and everyone on each chain would have to be considered honest and posessing a reliable memory. There is an entire
Science devoted to the study of the hadith.
Basically the Quran is the ultimate authority in islam. The Quran can abbrogate itself, and it does so in places (e.g. the prohibition of alcohol), but the hadith can not abbrogate the Quran.
Muslims pretty much agree on the scripture/beliefs. In the past there were sects who had variant beliefs in certain matters (e.g. whether the Quran was part of creation or not, whether believing sinners would reside in hell for eternity etc.), but through historical processes (mainly scholarly debate) these have been eliminated. So for example all muslims nowadays believe that the Quran is uncreated (i.e. it is the speech of God) and that believing sinners will not have to reside in hell for ever, but will be forgiven.
As you point out Muslims are split into many sects. However the overwhelming majority of muslims belong to the same sect - so called sunni's. The other major sect (about 10% of muslims) are the shias. The difference between sunni's and shia's is actually more political in origin than anything else - to do with the authority of who was the rightful heir to the Prophet (peace be upon him). Sufism is very much part of mainstream islam. Roughly speaking it is concerned with personal spiritual development. Having said that there are people who call themselves "sufi's" who are not even muslim, and others that lie on the fringes of islam. As mainstream muslims Sufis follow the Quran and Sunnah. But there are other texts (e.g. the work of Imam Ghazali) that are considered "Sufi" texts because they deal with aestheticism and worldly renunciation.
One of the best sites for both the Quran and Sunnah is islamicity (link below).
Other than the Quran, and the works of hadith there are also many other texts of islam by scholars on various subjects, some of which are considered classics (like the works of Imam Ghazali) and have become part of mainstream islamic heritage.
I hope I have answered some of your questions. May God forgive me for any errors/omissions in what I have said, and may God guide both you and me to the truth.
http://www.islamicity.com/