The other day the ping pong ball bounced to person 1's side of the table, bounced off his chest, then surprisingly bounced back on person 2's side of the table. Is that legal play or a foul?
See this question answered previously. The ball cannot be hit by someone's chest - only their hand (that is holding the paddle) can contact the ball.
Who wins a point where the ball hits a player in the chest would depend on whether or not the ball had already gone over the edge boundary of the table yet or not. If the person was leaning over the table when the ball hit them in the chest - it would be their opponents point. It the ball had already gone past the edge of the table the point would go to the person that got hit in the chest.