Does the 27 inch iMac come with iWork already installed or do I need to buy it separate?
In most of them, the iWork comes pre-installed. The very first version of iWork, iWork '05, was announced on January 11th 2005 and the stable release iWork 9.1 was released on July 20th 2011.
It can come pre installed but you have to pay $50 for it.
Or get it free from here http://tinyurl.com/77zw2rp its legit