As a high school tennis coach, I can only address the Tennis question.  Players can NOT jump over the net.  A players racket may NOT touch the net.  The racket can go OVER the net, as long as the player strikes the ball on his/her side of the net and then follows through over the net (without touching the net).  The only time a player can strike the ball while it is on the opponent's side of the net is if the wind blows the ball back to their opponent's side of the net before he/she has a chance to hit it back.  Hope this helps.