You said: "If you update a document on your Mac, it would automatically update the same document on an iOS device and vice versa."
That would be nice and is actually the reason for my involvement in this discussion to begin with.
With iWork applications (Pages, Numbers, and Keynote), updating a doc on my Mac WILL NOT update it on iOS devices without many other steps. Similarly, updating on an iOS device WILL NOT update it on the Mac.
On the Mac, if you change a document, you need to either:
A) Share it and it will be copied to iWork.com. Then you need to download it from iWork and UPLOADED it to iCloud. Then it will be available on your iOS devices. For iOS updates, you do the approximate reverse of this process. It will also be available on iWork for other Mac systems you own.
B) Upload the document manually with your browser to iCloud to make it available to the iOS devices.
This is why I maintain the marketing people and, unfortunately, including Mr. Jobs, lied to us last spring about iCloud. iWork applications for Mac are NOT part of iCloud.
You could store your files on Dropbox or similar services and they would be available to iOS. However, they are available on iOS only as read only. Updating them is a pain as they will be versioned with numeric text appended to the file name for each version.
You can (until either June or when you turn on iCloud), use iDisk which is properly designed to provide sharing of a file system between the Mac and the iWork applications on iOS. But it is being removed from Apple.
Good luck
