A player cannot reach underneath the net to contact a ball. If the first contact is a block, then the next play on the ball is considered the first hit. Any time the ball is set over the net, the setter must be perpendicular to the net. It is legal to set the serve, no matter if the setter is perpendicular to the net or not. As long as it is not lifted.
Double hits are legal because it is a hard driven ball.
It is legal to double hit a hard driven ball momentarily, but only on the first team contact or hard driven ball. Teams must establish a service order and maintain it throughout each game. A serve can take place anywhere behind the back line. The server cannot step on the service line to serve, or step over the service line until the ball has been contacted. If the server serves before the whistle by the official, it is automatically a side-out.