1) pick ups resitance is a few hundred ohms each pair of wires, about 300-500 IIRC. Check the voltage output from the pick ups 4 block connector when you crank the engine, a moving needle meter is better than a digi meter here as the voltage is changing. ( pick ups are just generating a small voltage when the rotor sweeps past- just enough to signal the ignitor)
set meter on 10v or less and probe pick up block connector lead pairs
red and yellow then black and blue
spin the motor and you should see the meter needle twitch as the pick ups generate a small voltage as the rotor sweeps past, Check both pairs.
Also with ignition on you can sweep past either pickup with a magnetic tip screwdriver and it will cause it's coil to fire. (two coils, for cylinders 1/4 and 2/3, one pickup for each. A 'wasted spark' system as it fires twice as often as it needs to.
2) no the only common connection is the red ignition live that feeds both coils in parallel.
Here is a US model 82 R1 wiring diagram.
kz.bike-night.com/media/Z750-R1-US.jpg
Common no spark faults are the clutch / sidestand / nuetral interlock on the ground side, also killswitch and keyswitch wiring on the live side.
There is a thread currently on GPz550 forum that covers the diagnostics of the ignition system for no spark faults,