I'll answer your PM (private message) and your other questions here.
There are 2 main types of 1/12 road course cars:
T-bar (aka T-plate)
or
link

The darkside Mx2 chassis is a link car, using pivot balls and links for the rear suspension. It's similar to this car:


This Associated 12L4 is a T-bar car. Notice the T-Bar fiberglass piece in the rear.


Check out this thread for more pictures:
http://www.rctech.net/forum/showthread.php?t=140902

You'll want a mini servo. Futaba 9602, JR3650, JR2550, KO949 are good examples. Some are analog, some are digital, so you need to be mindful of your receivers capabilites.