Questions:

1. I added V4 to a blank scene and then added a props (Briana's Temple) to the same scene. But then the main camera won't use V4 as its pivot. How do I fix this?

Answer:

1. You can make the Main or Aux camera orbit  round any element in the scene by simply parenting the camera to that element (Object > Change Parent). I recommend that you zero the Orbit dials and the X and Y translate dials of the camera, then memorize the camera before parenting it. Sometimes you may need to Restore the camera after parenting.

Whilst you could parent the camera to the head, hip, or BODY of your figure, I don't recommend that. A better way is to parent the camera to a square or box primitive, then move the primitive to whatever position you want the pivot to be in, then hide the primitive (Object > Properties > Visible).

As an alternative to the above, you could use Posing Camera which should parent to the selected figures Hip and move with it. The Posing Camera  can act a bit flaky when there are multiple figures in the scene. Even better in my opinion, use my "Tracker Cam" available for free from:

http://www.sharecg.com/v/26856/Poser/Tracker-Cam

Tracker Cam will automatically parent to the selected figure, and if you follow the instructions it will track (move with) the figure as you move it about the scene. Tracker Cam is (IMHO) better than the Posing Camera, as it will not bounce with the hip in an walk cycle or BVH, and the style of tracking is highly configurable.  

Note that using using "Point At" will not change the focus of the orbit of a camera, only keep it pointing at the target from whatever position it is already in.