Noob needs help

OK, I'm the guy that recently bought a 2012 FJ Cruiser that was pre rolled, probably low speed off road rollover. No regrets buying it that way, I love it. Turned out no motor mounts were broken. It's a real conversation starter as everyone assumes I rolled it. I just say yeah, you should see the car of the guy who took my parking space. It had plenty of dents already so it was fun adding some scratches without worries while I recently spent two weeks going all over backroads in Nevada and other counties. If not for the GPS on my iPad I would still be lost. Anyway, I am such a noob that I don't know what options this 2012 automatic 4WD came with, and which ones are working properly. Pretty sure that with the Bilstein shocks it must have the offroad package.

There is an issue with the warning light icon staying on that shows a car with skid marks (is that traction control?) The dealer did a diagnostic and said the chip in the master brake cylinder was bad and the whole brake assembly would need to be replaced for over $1800. I am not convinced it couldn't just be a sensor on a brake thats bad. The front driver side had a stabilizer bar tie that had broken in the rollover. I often feel a thud when I let off the brake. Could be related to this light being on. My brother thinks it could be a stuck brake caliper that I feel releasing when the car starts to move forward.

Pushing the skidding car icon button does not do seem to do anything, and I assume it is because of the chip issue. Also can someone explain what A trac is and how I engage it and how to tell if it is working? Same question for the RR diff lock button. I am embarrassed to say I don't know how these things work and what they do.

Even without these I was able to do a lot and got a pretty good feel for the strengths and limitations of the truck. I'll try to post pics or video when I get time.