US Government pulls "atomic cookbook" off the Internet

The US Government has had to pull a website containing a wealth of documents seized from Iraq which included in-depth details of how to build a nuclear weapon, according to the New York Times. The interesting thing is that these documents show that Saddam Hussein was only a year away from building a nuclear weapon back in 1991. The NYT document also says the documents were identical to internal IAEA documentation presented to the UN by the US in 2002.

Firstly, why did the US Government fail to notice that they had posted an atomic weapon cookbook on the Internet? Second, how these IAEA documents come into the possession of Saddam Hussein? Third and finally, if he was a year away from success in 1991, what would've happened if we'd dropped sanctions as many people were lobbying for?