SELECTING THE GYRO

the basic controls are
1)throttle
2)rudder
3)elevator
4)aileron

so we need atleast 4 channels to control.for gyro selection ,any gyro will do having sensitivity more than 50deg/s and gain we can adjust later according to our configuration.
working of gyro:when gyro is not getting any signal(to varry speed)from rx it will uppose the movement (on a paticular axis) by providing +ve or -ve signal to ESC and thus controlling the motor.
But when a signal comes from the rx it let pass that signal to esc.so we can varry the speeds manually

For microcotroller approach,i m going to post later, we need only sensor of gyro ,ie. VCC,GND,OUT pins are needed.
there must be atleast three gyros,one for each axis (X,Y,Z).
piezo gyros are very commonly available and cheap gyros,if you want the heading hold feature you should buy a HH(heading hold) gyro.