Here's what I learnt. First, some correction of what I previously said. Both my Nikkor 50mm D lens and 70-300mm G lens DO talk to the Nikon SB-900 seamlessly in automatically adjusting the flash convergence angle based on desired focal length.
But of course, you can always override it by setting it to the Manual Zoom on the SB-900. I have yet to fully grasp when a repeating flash mode is most ideal. Most pros would recommend the Even illumination pattern for minimal light fall-off at corners.
Always shoot with SB-900 sound option "on". It helps us confirm that the flash did indeed fires when you release the shutter with that few series of beeps. With that in mind, you now can start the journey of shooting with the SB-900. The rest is about creativity.