Valve Cover Installation Torque and Sequence

1999 Nissan Sentra GXE 1.6L Engine 16 valve Twin Cam
What is the installation Torque for the screws on the top valve cover gasket (aka rocker cover gasket) and is the square (or rectangular?) gasket underneath it always necessary to change too?

What is the sequence for retightening the screws and at what "turn interval"?

Thanks !

well you should replace it but thats up to you ive never tried so i dn it might leak but the torque sequence is easy just go from the middle on each side and work your way twords the edges and just kindof make them hand tight or about 18ft lbs