Sure it's not easy, but the shots individually arent hard, syncing up all 3 in perfect timing is.
And ya, it's very much unlike actual shooting.
Oswald didn't have the chance to practice over and over, but he also didn't have a set of shots he was trying to match perfectly, so it was much easier for him.
Pulling off the correct shots in JFK reloaded is actually not that hard. The issue with getting a perfect 1000/1000 is how stupidly perfect your timing needs to be, down to the exact millisecond. The accuracy and ballistic trajectory of the bullet is easy comparatively.
Did you try backing the plywood with a piece of hardwood while drilling? If you can clamp the two together that will work even better.
In most newer cars (not even that new, pretty much everything in the last 20 years) computer only fully shuts off if the battery is disconnected. It continues to monitor the car even with the engine off and the key out.