MediaWiki may be the right tool for the job. Though, I am not enough a techie to know if the amount of work needed to achieve the improvements you cite will require more or less time than a brand new software.
Ok, I hadn't seen the thread next door ("software improvements") :)
-- Guillaume Paumier [[m:User:guillom]] "Go confidently in the direction of your dreams. Live the life you have imagined." Henry David Thoreau