I don't think you'll get a clear picture from just the Quran. Most of the 'prophecy' comes from a hadith or hadeeth from what I gather a hadeeth is from someone who adds to what is written or gives more than what the quran does.
Look in the hadeeth section
http://www.usc.edu/dept/MSA/
Book 36, Number 4272:
Narrated AbuSa'id al-Khudri:
The Prophet (peace_be_upon_him) said: The Mahdi will be of my stock, and will have a broad forehead a prominent nose. He will fill the earth will equity and justice as it was filled with oppression and tyranny, and he will rule for seven years.
Book 36, Number 4273:
Narrated Umm Salamah, Ummul Mu'minin:
The Prophet (peace_be_upon_him) said: Disagreement will occur at the death of a caliph and a man of the people of Medina will come flying forth to Mecca. Some of the people of Mecca will come to him, bring him out against his will and swear allegiance to him between the Corner and the Maqam. An expeditionary force will then be sent against him from Syria but will be swallowed up in the desert between Mecca and Medina. When the people see that, the eminent saints of Syria and the best people of Iraq will come to him and swear allegiance to him between the Corner and the Maqam.
Then there will arise a man of Quraysh whose maternal uncles belong to Kalb and send against them an expeditionary force which will be overcome by them, and that is the expedition of Kalb. Disappointed will be the one who does not receive the booty of Kalb. He will divide the property, and will govern the people by the Sunnah of their Prophet (peace_be_upon_him) and establish Islam on Earth. He will remain seven years, then die, and the Muslims will pray over him.
I'm still looking for the reference of the Madhi coming against and establishing himself in Jerusalem (Baitul Maqdas)
Understand I do this out of curiosity and nothing more ever since I began hearing on the news about what Ahmadinejad was squaking about.