Re: hancom office question
Welcome to Android Central! I'm testing out a Galaxy Tab S, and on any of the Hancom Office apps (e.g., Hword 2014), the opening screen should show a Cloud option on the left column. Tap that, and you should see Dropbox, Google Drive and One Drive. You don't see that?
Have you considered just using Google Drive, with Google Docs, Google Sheets, and Google Slides? These apps are getting more and more powerful, and have the advantage of tight integration with Google. You can work on documents offline, and they will sync to your Google Drive in the cloud as soon as you get back online.