My brother was teaching Tai Ji Push Hands, Tai Ji Qi Gong, Tai Ji Qin Na and Southern Shaolin Tiger Form in Pan Chiao, Taipei, Taiwan in the late 80's and early 90's. Yes, he has a Kou Shu studio. He also teach in Taiwan's Air Force Academy for a short while. He was invited to do Qi Gong study in Harvard University. He was a honor guest in Japanese Qi Gong society and he was on TV in Japan that he healed 2 years old boy with Qi Gong. on and on.
I was introduced with Long Boxing first. Only to learn Tai Ji at later age. The truth of matter is that it is all in the state of mind. When you are in your teen, you practice Long Boxing would be better for growth and development of your musculoskeletal system. When you are under teen, no serious Wushu training. It would impair growth and even cripple you. When you are close to adult you may practice Tai Ji. You may practice Tai Ji at any age. But your state of mind is not ready. When you practice Tai Ji from adulthood onward. The older you get, the more proficiency you get, your Tai Ji Gong is deeper.
You may teach Tai Ji as exercise or meditation. However, Tai Ji Fighting is not for everybody. You need some talents and lots of practice. The theory of Tai Ji is that everything is moving, everything maybe defeated. Yin and Yang are born together and end together. In the extreme of one seeds the birth of the other, thus the opposite color of the eye in Tai Ji Yuan Yan Fishes.
When you teach any Wushu, you have to teach offense (Yang)and defense (Yin) at the same time. The student would learn a balance mind. The only way to win is to outskill and outsmart the opponent. Aquire the opportunity. Aquire the time. (Der Ji Der Shi). When you practice Tai Ji Push Hands, 4 Zhen 4 Yu. You are basically learning to listen and understand the nature of the opponent's Jin (direction, change of direction, intensity). Tin Jin and Dong Jin. It is all in the wrist and the forearm contact points. You are practicing sensing. Any moment you detect an oppotunity, you would do and think the opposite. If the opponet is going to retract, you push forward vice versa. (level 1). on and on. They are delicate training. Ultimately, you have to sense Jin with your whole body including chest. You end the fight by pushing or pulling the opponent. But you are practicing, you do not need to push or pull too hard. Actually, protecting your wrist and shoulder is more important. I was once injured on the right wrist and right shoulder.
Yes, if you need to push the chest, rule of thumb may be high up in the sternum only with a minimal force. The opponent is easy to fall, if you position yourself right. No need for a big force. Chest protector may be o.k. Head gears and mattress and learning how to fall safely are more important. If you actually want to make somebody fall.
Push Hands are about Don Jin, Tin Jin and think and move the opposite way (level 1).
A lot of times, you control and push the forearm near his chest to make him fall. not so much pushing chest directly with your hand.
If some student wants to learn how to beat somebody up. At first he has to learn how to defend and how not to be beaten up. That is the main lesson in Wushu.
Ignore my ignorance.