For the ESC I would go with the Mamba Micro Pro 1/18, not the older Mamba 1/18 or Sidewinder 1/18 (which are pretty much the same thing). Some people even move up to the Sidewinder 1/10 for running really hot (performance, not temp) setups in their 1/18 vehicles.
http://www.castlecreations.com/produ...micro_pro.html
For the motor I would suggest trying the 5400kv first before the 6800kv, should be plenty fast and will have a little more torque.