This is a work in progress, as I tune both the quadcopter and my CSS.
This project uses Multiwii for flight control, go here to learn more about it. Multiwii is an opensource flight software for multicopters, planes, and helis. It runs on arduino-type boards. Crius and other manafacturers sell integrated arduinos with an mp6050 3 axis accelerometer and gyroscope. Stock boards may also come with barometers, magnetometers, and GPS. Using the arduino i2c you can add external accelerometers, GPS, and more for functionality.
This picture shows the quad using 10x4.7 inch props with a 4s 4000MaH battery, on 2830 215 watt motors with 30 amp speed controllers. In this configuration it can lift up to 2 kg of additional weight. It is seen hoisting a tacobell bean burrito.