Gas Sensors with Arduino + Interfacing Circuit
You can connect the directly to the Arduino +5, Gnd and Signal.

I don't know of any calibration data for the sensors that I have.  I suppose you could take the maximum concentration the sensor can measure and divide this by 1024, but I don't know if the value returned is linear or logarithmic.
The data sheet does have some info on, but this page may be more helpful
http://forum.arduino.cc/index.php?topic=230945.0

Oh and don't forget the warm up time on the sensors!