Can’t say for sure, but I’m pretty sure the operation of them is different, considering the solenoid is different and the non neo need the extra drain for oil return, I can’t see them being able to be swapped.
If the spark plugs are out there is no resistance to build up. It definetily seems from here you have likely bent valves. Hope not but that would be a long shot
You won't hear a noise and in the case of a mis-timed engine turning over the contact is not normally large enough to leave a large mark or damage, but is enough to bend valves
How do you explain the extra resistance when turning over at some points? With plugs out it is the same to spin an engine over, no Change in resistance
I would be way happier with a ding in a piston than having just one replaced. Deburr it of course. It won't cause a hot spot, pistons already have notches for the valves, so a bit bigger isn't a deal breaker
Are you going to show us how to fit a different headlight into an r34? Whole assembly or just internals? I want to make sure my expectations are set correctly
The water isn't critical to use.
I would suggest driving it as is, then removing turbo for something more suitable once realising how laggy the car is.
I wouldn't say they are prone to snapping. They are prone to guys overtorquiing them when changing timing belts then they snap. It's not like a Design flaw or anything