Arduino 2WD smartcar motor and sensors shield

This is ongoing project.
I am designing Arduino shield for 2WD smartcar like [this](http://www.ebay.com/itm/Smart-Car-Robot-With-Chassis-And-Kit-Arduino-Controllable-New-from-USA-/252388565405?hash=item3ac387e19d:g:t7UAAOSwuMFUlixS)
The purpose is to create shield that will allow easy connection of sensors and control of two motors including feedback from motor speed sensors like [this](http://www.ebay.com/itm/Electric-motor-speed-sensor-module-Photoelectric-sensors-Groove-coupler-/1814601580