I have a 5D mk ii and a Tokina 16-28. I see that the Nikon 14-24 is an acceptable lens for VR panoramas and the Tokina is supposedly very similar to this lens.

From what I have read, the longer the focal length the better the resolution but the more pictures you have to take. I am tempted to pick up a Sigma 15mm F2.8 EX DG but since I have the Tokina and using this theory I can get better quality photos in the end it would seem to be redundant. I am gathering all my info from many places at this point trying to find the answers to my questions and I could use some advice...

Does anyone know where I can find how many images I should plan to take with this lens?

Does anyone have any thoughts on the Tokina 16-28 for 360 VR panoramas?

That and is the Nodal Ninja 4 the best panorama head for the 5D mk ii and the Tokina 16-28?

Thanks for any help!