Would this be a good steering servo for my Nitro Evader ST?
 

Would this be a good steering servo for my nitro evader? http://www.hobbypartz.com/topro55dircs.html

And it has all metal gears, correct?

That would probably be ok, it is pretty slow though .24 isn't that great. It is metal geared. I'm not sure what kg is in torque, those servos are made in china and they go by different units than the us. If it is over 100 oz./in. of torque it is pretty good.

I would not get that servo. It's pretty slow and it does not have the strength for steering. Check out a servo that is in the .12 or better range for speed. I would also look at a servo with 150 oz or better of torque.