If you're new to 3DOF controllers altogether (and who can blame you if coming from the Vive) you're probably new to VR on mobile platforms e.g. Gear and Daydream. One way to start is to see what is out there on the markets specifically if you have a Focus, try as many titles already available on Viveport.
1. Yes, the controller is only 3DOF, while the HMD is 6DOF.
2. It is possible to move the controller in a rudimentary fashion, as Dario pointed out, you can use the arm model for that. I think there's an example in Unity, otherwise I think you can copy the Daydream implementation in GVR. And I believe the Focus manual also says something about this. It's not great, and not suitable for new users, but it does work. I've used the touchpad to move the controller forward and backward, making it somewhat possible to interact with things. But again, it's not great.
3. I read that the 2.0 firmware will support camera tracking of the 3DOF controller, enabling 6DOF as long as you look at it. This will undoubtedly work better than the solution described in point 2. But I'm sure it's coming "soon". Let's hope that's not in Valve time. Otherwise, the Finch Shift looks awesome, but I haven't been able to find anywhere I could order it.
6DoF is now out... I am currently using the latest SDK and I am having issues with it distancing it self from the Focus View... feels further then normal (scaling issue?). I am currently using a simple short ray/laser and trigger event to parent the object to the controller. I would like to see something a little more realistic for throwing, etc.
Has the SteamVR/XR code been updated to support Focus Plus?