Good posts.
In Tai Ji, you think small and fine movements. You punch me. I punch you back. That is the gross response. In Tai Ji, you punch me; I pull you. You pull me; I press or punch you. (the opposite)
True. Yin and Yang happen at the same instant.
In push hands, you contact, listen and understand the direction and amplitude of the opponent's Jin. How do you stick or follow? You have to anticipate his moves. Right before his Jin changes direction, you have to sense and know. When the opponent starts to go in the other direction, you follow and add to it.
Sort of you are in contact, you sense, you know, you follow when he goes.
Yin Jin Luo Kong. (To guide and empty his force)
When you try to hit or push or pull the Tai Ji'er, you feel your force is emptied out. Because TJ'er use Chan Si to contact and merge into your force and guide it further beyond the limits of full stretch of your arms.