Microsoft OneDrive is needed to store Office files for smartphones and tablets. OneDrive is really pretty good - a lot like Dropbox.
If you sign up through this referral link, you will receive an additional 0.5GB of online storage:
Keep in mind that Hangouts, on computers, phones, and tablets, can accommodate up to ten people at a time. As the primary speaker changes, the image on the device changes to correspond to the speaker. It is pretty good.