I run PVL's on all my vintage KTM's. No issues.
1. I always run an dedicated earth wire from the stator backing plate to the coil/kill switch earth.
2. I have seen the wires that run through the back of the stator plate get pinched when mounted. I usually unbolt the stator off the mounting plates and reroute the cables so they don't run through the hole in the plate.
3. I usually buy a new NGK red resistor-less cap and solder on the HT lead. but my last bike i used the original cap supplied and haven;t had any issues.
4. Yes there are different number of winding stators, and got caught out with a second hand one off a go cart once. You will not start by kick starting...swapped out for the right number of turns, and it runs first kick. Also there are analogue and digital setups...
To test a used ignition, i have set them up in my drill press using a bolt through the rotor, and stator setup in the vice. Just to prove it works.
Earth wire on stator plate.