Copying a document by email should result in a duplicate in iCloud. It would not update the original on the iPad, but it should have copied the new document to the iCloud and showed up on the iPad as another document.
Since the iPad did upload the documents, your problem is on the iPhone. Please excuse me if/when I repeat anything you've already done. I know you said you were set up right, but lets go over it again so that we are on the same page.
On the iPhone in Settings > iCloud check your account name and re-enter the password so that you are sure it is correct. Make sure that Documents & Data are turned on.
In Settings > Pages (or other iWorks app) make sure you've turned iCloud on. If it is on. If all this is good, then I've got one other thing to try.
Do this only if all your documents are on the iPad, or safely stored off the iPhone somewhere else. Go to the Settings > Pages and turn off iCloud. Now open the app. When it asks you, go ahead and have it delete all the documents from the iPhone. Delete any remaining documents manually (just so we are sure what does and does not sync). Close the app. Clear the app out of RAM by double tapping the Home button for the multitask bar, tap and hold on the Pages app until it jiggles, and tap the minus sign.
Go back to Settings > Pages and turn back on iCloud.
Open the Pages app, and patiently wait for it to try and sync to the cloud. This can take several seconds to start, and depending on how many documents you have several minutes to finish.
If it does not sync the documents from the cloud, there is a big part of the problem. To make sure it is talking to the cloud at all, create a new document and see if it uploads.
I tried all of this on my iPhone 4 while on my home internet connection and it worked fine. I also updated a test document on both devices and they synced.
Good Luck.
