Useful info in this link about setting up Unity
From Unity 5 docs:
DEPLOYING TO THE GEAR VR
To set up your environment for Gear VR development, you’ll need to set up both Unity and your phone for Android development first. Keep in mind that the consumer GearVR supports the Samsung Galaxy S6, S6 Edge, S6 Edge+, and Note 5 handsets only at present:
Enable developer settings on your phone by following this guide, then enable USB debugging on the developer menu.
Finally, follow the detailed instructions on the Oculus website on building for Gear VR.
Do take note of the requirement for a Assets/Plugins/Android/assets/ directory, and the accompanying OSIG files, which are required to deploy content on your Gear VR. To help remind you, we have placed a Readme.txt in that directory of the VR Samples project.
Remember that if you are not distributing your Gear VR content via the Oculus Store – perhaps sending builds to be reviewed on colleagues devices – you will still need an OSIG file in that directory for every device your content needs to run on.
PUBLISHING ON THE OCULUS STORE
To publish your project to the Oculus store(s), please see the publishing documentation on the Oculus site.
PUBLISHING ON OCULUS SHARE
Oculus Share allows you to share your DK2 VR games and experiences with the community, and receive feedback from users all over the world. It’s a great way to distribute your work and gain valuable insights from players.