From: Sealed box size for x12, 4 ohm with BP

I've got the box built, and am ready to mount the sub into the box. I need to know what size screws to use and Do the screws go through the top of the gasket, through the frame and through the bottom side of the gasket into the box, or do I lift up the gasket on top and just put the screw through the frame and through the bottom side of the gasket into the box? And Do i need any caulk or gasket material between the box and the sub for sealing?