Sorry for adding to the list of stuff that may or may not be useful but here is a link to another site with a pile of technical manuals and other repairing resources.

http://www.ifixit.com/Browse/Mac

As I said before, good luck with your repairs, mind you from the description unless you have a techie type of background it might be simpler and quicker to take your iMac along to a service centre and let them deal with your computer problems.

Cheers,

Andrez