How to use iCloud as main storage location for all documents, application files, etc? I have an iMac, Macbook Pro and an iPad Pro, but I'm relatively new to the IOS/OSX ecosystem as I've only used these devices for very specific use cases. I'm in the process of making the switch to all Mac. As part of that quest, I signed up for iCloud and I'm paying the monthly subscription for 2TB. Since that amount of storage is greater than the sum of all of my devices, I would like the apps that need to save files somewhere to all save on iCloud. This way I can access those files from any device without having to think about which device the files are on, or having to make sure I sync the files or folder. 

Is this possible? Is it even a feasible idea to use the cloud in this way?
What you want to do is possible, assuming your internet connectivity is good on all devices (which I assume it is) and that they’re running a supported version of iOS and macOS.

More specifically, iCloud Drive requires iOS 8.0 or above and Mac OS X Yosemite or above.

If your Macs are running macOS Sierra or above, you’ve also got the option of Optimized Storage. I encourage you to read How to free up storage space on your Mac for detailed information.

I also encourage you to read Manage your photo and video storage to help you understand the best ways of doing this on iOS devices if you’re wanting everything stored online.

And, assuming you’re running iOS 11 or above on your iOS devices, you’ll want to use the Files app. Read Use the Files app on your iPhone, iPad, and iPod touch for more information.