When standing the elbows may come forward to hold the instrument away from the body. In this case keep the line between the two elbows parallel with the line of the shoulders and body.

You need not stand on stage like a wooden puppet of course. Some performances demand showy movements. But try to remain aware of your posture while playing, and the effect it may have on your tone, your state of meditation, and the danger of RSI (repetitive strain injury).

D.
Against the outside of the right leg, about halfway between hip and knee.

E.
For the sax the mouthpiece angle is about 60° - 75° from the line of the body, for the clarinet the best angle is about 35°.

F.
Dropping the jaw.

G.
1. The wrists are held straight and in line with the lower arms.
2. The left thumb is pointed upwards, the octave key is operated by flexing the thumb joint.

H.
The side Bb is pressed with the palm of the hand
The side C is operated by a rotational movement of the hand (touching the key with the side of the hand near the index finger knuckle joint).