Car stalls and weird noise when turning the wheel

My car has the nasty habit of unexpectedly shutting off on me. Yesterday I was a street light and I lost all engine power. Then I put it in neutral, tried to restart. Nothing. Then in parking, and I managed to restart the engine, from there I got home (about eight miles). But this has happened multiple times now, and I had the crank sensor replaced about eighteen months ago (at the time the car was already above 70,000 miles). It just passed inspection, but this worries me to no end. No mechanic can even tell me what is wrong with the car, other than telling me it can be any number of things, and because of how spontaneous the problem is it is impossible to test for it.

My second problem is that for the last 1,000 miles or so the car makes a weird almost grinding noise whenever I turn the wheel usually when the engine is still cold.

Lastly what is a fair price for getting the power steering belt replaced. I went to a shop they told me $1,000.00 that seemed rather high.