The Quran never encourages meaningless prayer. If some Muslims do this...it's because they are following an empty, ritualized faith that they probably know little about.
The Quran also never mentions anything about women being ritually impure during menstruation. (2:222 is about not having sex with menstruating women...for health reasons as well as the fact that women are frequently in pain during this time)
It's very likely that the Muslims picked up this tradition from the Jews, who I believe DO have a concept of women being ritually impure during menstruation. Hinduism and Zoroastrianism also have menstrual taboos.
It's interesting that there are many ahadith on the subject...some quite interesting:
Book 003, Number 0587: 'A'isha reported: The Messenger of Allah (may peace be upon him) said to me: Get me the mat from the mosque. I said: I am menstruating. Upon this he remarked: Your menstruation is not in your hand.
There are others like this as well:
Book 003, Number 0591: 'A'isha reported: The Messenger of Allah (may peace be upon him) would recline in my lap when I was menstruating, and recite the Qur'an.
I'm skeptical of the ahadith...since they were collected so many years after Muhammed...but these go against the grain. They are not what we expect from a Middle-Eastern culture of the time...as they actually go against what was commonly practiced. Ex. Aisha was reluctant to enter the mosque while menstruating. There would be little reason to manufacture them to lend authority to someone's personal desires etc. There are also other ahadith that report the Jews getting angry at these new ideas about menstruation...and saying, "This man does not want to leave anything we do without opposing us in it." (I will provide the entire quote if you're interested)
Divorce is not supposed to be the say it three times and you're out stuff. It's supposed to be a rather lengthy procedure involving three periods. This is another distortion of the Quran.
Re: Only Muslim men marrying outside the religion - Some Muslims are actually arguing that this may even be a distortion of the Quran. I will try to find their arguments for you if you're interested.
Re: adultery - "The woman or the man guilty of adultery or fornication - flog each of them with a hundred stripes" (24:2)
I find the following one of the most interesting passages related to this subject:
"Let no man guilty of adultery or fornication marry any but a woman similarly guilty, or an unbeliever" (24:3)
In other words, the macho idea of men sowing their oats and then getting a chance to marry a virgin is given a death sentence with this passage.
Or how about this:
"And for those who launch a charge against their spouses, and have no evidence but their own - their solitary evidence can be received if they bear witness four times by God that they are solemnly telling the truth; and the fifth oath should be that they invoke the curse of God on themselves if they lie."
"But it would avert the punishment from the wife, if she bears witness four times by God that her husband is lying; and the fifth should be that she solemnly invokes the wrath of God on herself if her accuser is telling the truth"
(24:6-9)
So, the husband can accuse the wife of infidelity, but the wife's oath trumps her husband's.
These are all pretty remarkable ideas for a book that everyone's saying is so terrible. The fact is...it's the people who are misrepresenting the book that are evil..not the book itself.