Traction control light on

Check fluid level and condition in the brake master cylinder. If it's got sludge on the bottom (use a screwdriver to check) flush it with denatured alcohol and replace with clean, fresh fluid.
Have the codes scanned. Check the air gap on the wheel and vehicle speed sensors.

The lights flashing intermittently may be because the computer stored fault codes and just needs to have the memory cleared.
The brake light flashing could also be a short in the parking brake switch or wiring. The fact that the lights go off when making turns leads me to believe that it is a wire shorting out, being pushed against a grounded metal component due to centrifugal and centripetal forces during cornering. Find the switch on the parking brake mechanism and trace it as far as you can, looking for worn or broken insulation. At least wrap any suspect areas with electrical tape. Then, disconnect it from the switch and take it for a drive. If that causes it to not flash, replace the switch.

Brake pedal grind is usually caused by metal to metal contact in the brake system, but you said the pads and rotors were already changed. Was that just the front or the rear, also?

Check around the steering column for any binding wires or wires that may been frayed or lost insulation near the column. Your car isn't a drive-by-wire type, so it can't be a short in that kind of system. In order for the lights on the dash to be caused to flash, their path to ground has to be completed. I have attached schematic diagrams for the ABS circuit and for the instrument cluster in hopes that they will help you trace the fault.