Why are my iWork files not syncing across devices?

I think my confusion stems from the fact that there are two different things that sound like they have an identical purpose: iCloud, and iCloud Drive. I have always thought of iCloud as a sort of virtual storage drive for backing up documents and such. But now there is iCloud Drive on top of that, the purpose of which is to... back up documents and such?

Before iCloud Drive, there was just iCloud. This behind-the-scenes service backed up all my Pages and Keynote files without me having to do anything besides turn it on in the settings. Updates were backed-up to the cloud and pushed out to other iDevices automagically. It was great.

Now (well, in 2015) there is iCloud Drive, and I am not really sure what additional service this offers above and beyond what iCloud was already doing.

What is obvious to me is that documents are no longer being taken care of for me. I now must manually manage the backup and sync process myself. See here, in the latest version of Keynote, none of my presentations are downloading automatically. I have to go through 200+ presentations and tap on that little cloud symbol if I want to download them to the iPad:

Furthermore, why do I have an option to go directly to iCloud Drive in the left pane? I should be able to go to Keynote to get a file, and Keynote should always pull down the latest version of it from iCloud. In other words, iCloud is where my apps go to fetch the documents I want to open in the event the latest version is not already on the device. I should never have to go to the cloud myself hunting around for files.

And why are the dates on these files so old? I have updated all of these files within the past 6-12 months , yet most of them show last edit dates of more than 2-3 years ago. That tells me my recent edits are not being backed up to the cloud.

And when I can't find my files, which now seems to be quite often, I resort to searching for them:

Why are there two version of this file, one on the iPad and one in the cloud? I made changes to this file yesterday, and I was working on this very iPad. Shouldn't the version on the iPad be the most up-to-date one? Yet that one shows a date of May 2016! Somehow the updated version of the file got backed up to the cloud, while the version that is actually ON the iPad is still two years old! WHY?

I want to update my presentation on the iPad, and then I want my iPad to back those changes up to the cloud and push them out to my other iDevices, so that every device gets the latest version. That is clearly not happening.

I must have something wrong in the settings. Let's take a look:

I have iCloud Drive switched on, and below that Keynote is also switched on. This tell me that Keynote should be backing up everything to the cloud. But above that, "iCloud Backup" is turned off! How can Keynote be backing anything up if iCloud Backup is tuned off?

How can it be possible to have iCloud Drive turned on, while iCloud Backup is turned off?

By the way, when I came into work today I pulled out an old iPad that I use as a backup and it shows this same file with a last edit date of yesterday at 9:38 PM. That's more recent than the May 2016 version on my current (newest) iPad but it's still missing many of the edits I made last night (I was working on this file well after midnight). That makes three different versions of this file between two iPads and the cloud.

I did read the iCloud Drive FAQ, but it's just not very helpful. And since I'm not clear on the difference between "iCloud Backup" and "iCloud Drive Backup", a knowledge base article that uses those terms just adds to the confusion.

I've been using Keynote on my iPad(s) for more than five years, and had always considered myself something of a super-user when it came to building presentations and using the iPad in the classroom. But recent "improvements" in both iOS and the app itself have made me feeling like a total newbie. I'm growing weary of so many learning curves being constantly put in my path.