Rolf my guess is since it is not always a guarantee the steering column will provide a good ground they add a ground wire to be sure you have one. As for the other question (no dash light indicator yet right turn lights work correctly) my first guess would be maybe a burned out turn signal bulb, turn signal bulb holder not making good ground (twist it a bit and see if it starts flashing) or somehow a wire that should go to it didn't get tied in correctly. Hard to say without seeing it. The left signal problem sounds like sort of the same thing...turn signal switch is sending out power but for reasons unknown it isn't making it to the wiring for front/rear turn signals.
