There is no specific mention in the official FIVB rules of a requirement to roll the ball back under the net to the opponent. However, actions which are contrary to "good manners" are considered rude conduct under rule 21.2.1 and therefore subject (on a first offence) to a penalty of point and service to the opponent. A second instance of rude conduct by the same player would result in explusion, and a third in disqualification. It would be possible for a referee to determine that throwing the ball over the end is not "good manners" and therefore sanction players accordingly. However, doing so without warning the players first would be (in my opinion) over-officious on the part of the referee.
Of course, there may be local rules in effect for whatever competition you are playing in and these would take precedence.
In answer to the question about professional matches, this question generally would not apply as there would be ball retrievers who would handle making balls available to the serving team.