A little late to the discussion, sorry.
Most cameras can be accepted by the SD cable networks. Interestingly, the EX cameras were the forst small sized cameras accepted by Discovery HD. They do not accept SD, HDV or the HVX200 P2 except for very limited use.
There are several Nikon lens mounts for the EX-3. The magification factor is 5.5X! Great for wildlife. But some of the cheaper Nikon lenses can look a bit soft, have a lower contrast or more chromatic aberation. They are also not designed for follow focus or smooth zooming 'in shot' so plan accordingly.
There are 2 B-4 mounts. One with electronics enabled and one without. The electronically enabled mount is made by Fuji and provides all servo functions to the lens, enabling control of iris plus power to the zoom motor. It costs around $1700.