For the man. Stand with the back against a door. Head touching . Back touching including the small of the back. You will find the weight is over the heels. Raise the arms into the ballroom position. The magic ingreadient is flex the knees. This brings the weight from the heels to a point between the heel and the ball of the foot. This is where it should be.
I dont know about the rest of you but if I stand upright against a door and put my hips forward I get an arch in the small of the back and the weight stays over the heels.

"4. The ladies left elbow rests on the man's right elbow."

Rests? No, no, you hold up your own arm

So true Clumsy,
Sadly, many teachers instruct women to "rest" their left arms on the man's right, and at social dances, this is the cause of some of my posture problems. The concept of the lady "resting" her left arm, as in making light contact, is fine, but when they begin to drag you down via your arms, you know they haven't been properly instructed. And that's not right or fair to those ladies because many men will avoid dancing with them and that often results in a lady laying down her dreams of dancing to rest. If I know a lady well enough, I try to politely and respectfully advise her otherwise.