I am trying to find any information on Automotive Chassis, like what they do, and why they are important, and maybe how to repair them.
This is a strange question so expect some very unusual answers. The chassis the the structure and frame of the car. Everything on the car is supported by the chassis. The chassis will only need repair if it is damaged by an accident, rust, failure of some kind. You cannot repair a chassis without expensive hydraulic frame straightening equipment. Unless you are a welder and don't care about geometry.
The chassis is just the body of the car. Used to be just the frame, until they found a way to combine the frame with the body into a single unit. The drive system and running gear are ATTACHED to the chassis, but they are not part of it. Same for seats, dash, and steering column. Attached, but not part of. The chassis is the frame without the doors, hood, or trunk lid. It can be repaired by any body shop.
