A: Before you start the VR render, follow these steps to re-center your model in the viewport...
  1. To keep your project clean, make sure you create a new camera and rename it VR

  2. Make sure you have the model selected using the yellow Model Selection tool from the toolbar in the center top of the screen

  3. Shift+Ctrl+LeftMouseClick anywhere on the model to center it in your scene

(This will 100% every time re-center your model in the viewport, thus making your VR renders be centered as well. You can then check to make sure it's in the center by clicking on the camera icon from Camera Tab in the Palette and scrubbing through the "Azimuth" slider. This rotates the model and will allow you to double check that the model is definitely centered.)