JammedStab,
After consulting with some of our engineers I totally agree with your body gear/nose gear steering angles and ground speeds etc. However it was pointed out that your Captain from example 1 was more than likely incorrect, because if you are holding on the runway, your nose gear should be straight and therefore you body gear should also be straight and locked after nose gear angle is less than 20 degrees. If not, then you will get a "gear not centred" message on thrust lever advancement. Did you get that message on your takeoff roll? A continuous creaking noise does not make sense if you are holding/not moving but stranger things have happened in this game.
As for example 2, when performing a sharp 90 degree turn and feeling vibration through the steering cables and tiller, 2 things come to mind. 1... a dry nose gear steering collar as I previously posted or 2... nose wheels scrubbing in the turn due to entering the turn a bit too quickly. I have observed this in both wet and dry (nose wheels smoking in dry) conditions.
You are correct as far hydraulics (#1 system) are concerned. It was also pointed out to me by the engineers that you have a 7 degree limit both left and right for rudder pedal steering at low speeds (steering tiller inputs will override rudder pedal inputs) and if a nose gear steering cable breaks then a roller moves out of detent and allows the nose wheels to caster.