I've attended a couple race clinic's hosted by pros and the general consensus is a servo speed between 0.08 to 0.12 s/60°, it helps to have a computer radio which supports steering speed adjustment as well as exponential rates. In case you buy a servo that is too fast, then you can slow it down for your needs.

Torque is pretty much irrelevant for on-road cars, any modern name brand metal gear servo should do fine. I've even had luck with some off brand servos. Before selecting a brand, I would make sure you can easily find replacement gears just in case.