2
Well if the professional football player has the ball then no cuz if you go out of bounds then you go out of bounds so.
Yes if a player steps on the out-of-bounds line than the player is out-of-bounds.
In American Football, if a player has one foot out of bounds when he catches the football, he is out of bounds. If he has is in bounds when he catches the football then he caught it and it is a completed catch. If the player goes out of bounds and comes back in bounds and catches the football it is still an incomplete pass. However, if he was knocked out of bounds or if the ball was tipped, it may be a completed pass. The rules keep changing at all levels of the game.
The ball is not "out of bounds" unless the ball or the player who possesses it touches the ground in an out of bounds area. So in the case where the ball is in flight over the sideline, and a player who is inbounds catches it and demonstrates control before stepping out, the pass is complete.
can a defensive player step out of bounds and go back in bounds and be the first to touch the football
no
Depends weather he had possesion of the football and had 2 feet in bounds. If in fact he did not have both of those things then the play would be blown dead anyway. the player has to maintain possesion of the football and the ground can not assist in the catching of the football.
Professional football player
a football player
no, in fact they have a penalty for that
Reception
Rules vary from state to state but in this case it is perfectly legal. So along as the players feet are in bounds. In highschool football its normally if one foot is in bounds and the other is not out of bounds and the player has control of the ball then its a catch