The Qur'an is in Classical Arabic, i.e. the language spoken in early middle age Arabia. Linguistic evolution occurred naturally in the spoken varieties of Arabic, but Classical Arabic remained the standard for the written language, and the Modern Standard Arabic of today is based on Quranic Arabic.

The Quran would not be linguistically revised (beside its being sacred) because there would be no need to, because the language would be understood.

Also, when the Qur'an is "sung" in Arabic during periods of worship what are they really reading from and is it considered in bad taste to "sing" it in a different language?

Most devout muslims would be quick to warn you that Qur'an is not "sung" at all, but recited. Indeed, the word "Qur'an" itself means "Recitation/Utterance". This recitation, which has a certain flow and rhythm tied to specific traditional rules of pronunciation, is called Tajweed. Since "singing" is more easily associated with notions of entertainment and nonchalance, muslims don't use that term when talking about Qur'anic recitation, which, ideally, should be done with solemn mindfulness.

During prayer (Salāh) you recite short verses (surah) you have memorized from the Qur'an, in Arabic. When praying with a congregation, an imam leads the Salāh, so he does the recitation (the main parts, anyway) according to Tajweed; but when praying solo, since most muslims are not heavily trained in Tajweed, they just pronounce the verses as best as they can.

The question of whether reciting a translated version of Qur'anic verses in one's own language during prayer could be considered valid (halal) was an urgent discussion topic among the early muslim community, especially new Persian converts (Sarakhsi, Kitab-al Mabsud). Since the Qur'an is usually considered to be holy (and miraculous) both in meaning and language, it seems to have been quickly settled with a near-unanimous answer, "No". The only prominent religious scholar to allow it (reluctantly at that), afaik, was Abu Hanifa, founder of the Hanafi school, who has been said to renounce his decision later on (Al-Zamakhshari, Al-Kashshaaf 16/149).

You can still come across objections and challenges to this common view, but they are very few and far between. Yasar Nuri Ozturk, a popular and populist theologian from Turkey, for instance, is one proponent of the idea that you can use whichever language you're comfortable with—based on the Hanafi ruling I mentioned earlier—, but even he usually says that it's better if you can do it in the original. I also know of some modernist/nationalist late Ottoman intellectuals (author Ali Suavi, the famous poet Ziya Gokalp...) who, as part of their ambitions to Westernize the country, wanted to banish Arabic altogether not only from the secular realm, but also from the religious experience. They weren't entirely successful in their lifetimes, but some of their ideals came to be realized in the form of Ataturk's reforms which included abandonment of the Arabic/Persian alphabet in favor of Latin, and forcing the adhan (the 'call to prayer' hymn delivered from minarets five times a day) to be recited in Turkish instead of Arabic—an immensely unpopular decision that was rolled back in 1950, with the end of the one-party regime.

If this violates the rules, please remove the post, but this article in the NYT today talks about newly discovered Quran fragments that may date from right around the founding of Islam. There are a couple pictures of the script (called Hijazi, according to the article).