At least with Chin, they do allow passing, everything is using a "point-by" system, Novice you can only pass on approved straightaway's, the other levels are unrestricted. As for an instructor not letting you do "something stupid", that doesn't mean there won't be mistakes made. Hell, last time I was out, I saw one guy almost completely spin out right in front of me in Turn 17 @ Sebring, and another guy over shoot turn turn 7. An instructor can only do so much to help a person drive, so things will definitely still happen.
I think there have been many threads about making the Z track ready. The list is pretty short, so here you go:
1. Upgraded pads (I'm using Carbotech's).
2. Oil Cooler (It's a must, get a 34-row, can never have too much cooling)
3. Somewhat optional, Stainless Steel Brake Lines. I'd recommend it, easy job, and cheap. Much more reliable and more firm and predictable compared to the rubber lines you'd be replacing.
You should also do an oil change before an event, and most also require a inspection covering varying components before an event.
Here's an example of one:
Chin Motorsports Tech sheet