e420 head gasket

Hello from New Hampshire. I'm replacing the head gasket on my 1994 E420.I have the cd rom.I purchased the gasket set from the local M-B dealer p/n 119 016 35 20,119 016 36 20,119 010 50 21,119 010 52 21.The cylinder heads are off,cleaned up and ready to go.I have three questions to open with tonight.The old exhaust manifold gasket is a combination of three separate pieces of gasket material (Goetze p/n 12901-031)which are bonded to a thin strip of aluminum p/n 119 142 05 60.The new gasket is two thin pieces of aluminum bonded together with no gasket material p/n A 119 142 13 80 RNZ. I take it this is an upgraded part-am I correct? The tightening procedure for the cylinder head bolts calls for three stages in the correct sequence of 55 Nm + 90 degrees of rotation + 90 degrees of rotation.I'm curious why there are no exact torque figures for the second and third steps. Finally:what,when and where should I be using gasket compounds,loctite,etc. during the assembly process? Any other tips would be greatly appreciated. Thanks for the help.