re: The rings and where are the spokes?
I seem to remember a suggestion that the ring spokes were an electrostatic phenomenon - more of a case of being completely baffled by them than any hard scientific principle though.
Cassini hasn't spotted any yet, and its cameras are superior to voyager's ( plus it's come closer to the rings )
It seems to have been a transitory effect, and may be related to axial tilt and therefore the amount of sunlight falling on the rings ( the rings were much less 'open' during the voyager flybys )