My guess is the wheel speed sensors, wheel bearings, or ABS tone ring. That system is real finicky. A mechanic you trust should be able to check all that out. I do it a lot and I haven’t charged anyone before, unless they have me replace a wheel bearing.
The lights mean something is wrong. We can’t tell you much beyond that. Buy a cheap code reader so in the future you can scan the codes, and get a little bit more direction.
First things first, make sure your gas cap is on all the way. Pretty sure that can throw a code which will disable those things. Someone correct me if I’m wrong.
The hill start and traction control are dependent on the braking system, so the lights all come on at once - it’s probably that. Any work done recently? The power steering is odd… it’s electronic in the Impreza, right?