Tilting the rotors backwards is the same as `up elevator`. So which ever Transmitter stick you would use for elevator on an ordinary plane is the one to use for an autogyro, and back stick means down tail and up with the nose. Whether it is the left or the right stick depends on which mode you fly on.
Metal or plastic geared servos - Mine are plastic, adequate for a .15 powered model. In fact my .15 powered model uses some old servos, work fine, even withstanding some bad crashes!
My .35 and .40 powered planes use Futaba FP-S3001 with plastic gears - all fine so far.
Colin