I'm about to replace inlet manifold gaskets of my Peugeot 406 1.8 16V (XU7JP4 LFY) petrol engine.

Do I need to apply grease on new gaskets before installation? Some say it is necessary, some say the opposite! I'm confused!
I didn't find the tightening sequence of intake manifold bolts. Does anyone have the pattern?
Is the tightening torque 20 nm?
Thanks for your help.

When I was removing the manifold this thing fell into the intake port.