myservo.detach(ServoPin); // detaches the servo on pin 9 to the servo object
If you detach a servo, but still have the Gnd & +5 volts wires hooked up, is it drawing any current or holding it's current position?
That is really two questions, isn't it?
1. A servo that is detached (has no active control signal) but still wired to ground and +5vdc, will still draw some minimum amount of current. How much is specific to your servo. Simply measuring it's current draw with a multimeter will give you the answer.
2. A servo without a active control signal will to stopped, but can offer no resistance to external forces acting on it's output shaft. So it will hold position as long as external forces aren't higher then the servos gear reduction friction.
Servos were never designed to be powered up but without an active and continuous control signal. So while the Arduino servo library allows one to 'detach' a servo, that is operating a servo in a mode it was never designed for and it's exact characteristics and response to that situation is undefined by the servo manufacture. I can't really see a need or advantage to having to 'detach' a servo in standard servo applications, at least from the servo's perspective?