Everyone's forehand and backhand should be relatively equal, so that should be irrelevant. The partners should have specific responsibilities of the court coverage that they need to adhere to whether it is a forehand or a backhand. If your backhand is weak, practice it to make it better. The only exception to this is if a shot is hit high and soft through the middle. In that situation a high forehand takes precedence over a high backhand.
High volleys are easy.
If you make contact low on a groundstroke and lift up on it, the ball will go over the net. Not necessarily true. You need to lengthen your hitting zone just as you would on any shot. For whatever reason, lifting up on a low ball will actually make it go further into the net. Double hits and carries are illegal.