As to your lens distortion...
If you're shooting to make a photosynth, I don't believe this will impact you as Photosynth for Windows is resilient to changes in focal length. It doesn't handle shots from an ultrawide lens like a fisheye lens, but other than that I think you'll be okay.
If you're shooting a panorama, so long as you keep your focal length the same for all your input shots, I don't believe that ICE will care either. Again, ICE isn't compatible with ultrawide lenses like fisheye lenses, but within reason, I don't forsee problems.
With panoramas, so long as you have some way to keep the camera stationary, you can get a much higher resolution panorama if you shoot zoomed in as far as possible.