[Russell Sobie]

I pretty sure if your crew chief warns you for track limits it's an incident.
It's considered an off, even if you don't hit anything.

Nope. Going off track to avoid folks and getting a "cut track" even bad enough to trigger AC's horrible penalty system doesn't count towards incidents. Additionally, I've lost control overdriving the car and slide around in the grass alone and never got an incident for those either. JUST going off track means nothing for that value.

Does damaging the car on some part of the track count also? For example, when entering the Caroussel on Nordschleif, I often find myself damaging the bumpers as I get in the caroussel, is that considered an incident?

Possibly? As mentioned above, I've gone off track before and not received a ding, but I am pretty sure at least once I've gone off track into a divot deep enough where it damages my car, and that counted. I think. Maybe it only counts non-car/car collisions if you are off track?

My understanding is that it is only collisions with other physics objects, and nothing else. So basically cars, some cones/signage, and static collision.