<font face="Verdana, Arial" size="2">After that,connecting to Chin Pu Pan Lan Chi, is a movement in which the weight shifts to the left leg as the left hand cirles down to the right side of the body with palm up and simultaneously the right hand executes a clockwise semicircle over the left hand and stops ahead of the player's chin, in front.</font>
It sounds like the hand movement you describe is similar to the transitional Rollback that precedes Separate Foot to the Right, except that in that posture, the Rollback is done shifting the weight forward into a left Bow Stance. Yang Jun does not teach this type of hand movement, and we do not show a right hammer fist or chop to the opponent's right cheek.
Rather than moving the left hand to the right side of the body or circling the right hand clockwise over the left hand, we do the move as follows:
Shift the weight backward and open the torso diagonally to the left. Simultaneously with that movement, move the left palm and forearm in a "downward, then inward and slightly rightward, and finally upward" arc, in order to curve the arm into a "Wardoff" position. Simultaneously with those same movements, move the right arm from its "chambered" position by the right hip upward and forward in an arc as you rotate the fist/palm from facing upward to facing downward.
The final position of this transitional movement ends up in a Rollback in a backweighted right Bow Stance with the left arm curved in Wardoff and the fingers pointing about one foot away towards the Jin point in the middle of the right forearm. The right wrist is maybe about at the same height as the right shoulder. The right fist/palm and right elbow are in line with the right foot and knee. Your navel is facing diagonally to the left.
For the rest of the movement, you will then continue the downward, leftward, and rearward arc implied by the upward and forward movement of the right arm and the leftward waist turn in order to do the rest of Chin Pu Pan Lan Ch'ui (Jin Bu Ban Lan Chui or Deflect Downward Parry and Punch).
As far as I can tell Fu Zhongwen's movements look the same, except that in White Snake, he seems to re-form his right fist in the upward movement, whereas we do it in the later downward movement to the left as you shift all your weight to the left leg and lift your right toes off the ground.
As for applications, I visualize only a generalized movement of my opponent at this point, but can give a suggestion if you need detail. Imagine that as you strike with your left standing palm at the end of White Snake, your opponent uses his left hand to grab your wrist, push it aside, or deflect it. You then pluck his left wrist towards you and try to connect to his left elbow with the soft part of your right forearm. From here you can attempt Split or Rollback. If you fail and the opponent pulls away or tries to obstruct or trap your right arm, you "chase" with Deflect Downward Parry and Punch, moving your right arm in a big or small circle as circumstances dictate.
Does this make more sense?