It's a movie entirely about a mythical martial art and it's about achieving a very powerful fist that can punch without an actual physical contact. It's like if the fist got an extra invisible layer. I don't know how this fictional art is called in the movie, but I think it's about an iron fist...
no difference at all. your torso is still in the same position, intestines don't go anywhere and bacterias that digest the food aren't affected either. if you are obese there may be some slight pressure on your body but that shouldn't affect digestion. it's stupidity that makes these myths true...
why do you need someone? there will be plenty of people like you. just go there, observe, have a drink together with you or buy it, make a conversation if you want to.