The firing order is 1,3,4,2 #1 is at the left end as you look into the engine bay, the plug gaps depend on the engine code and plug manufacturer!
C18SEL all makes 0.8mm
X18XE1 Bosch/Champion 1.0mm NGK 0.8mm
Z18XE all makes 0.9~1.1mm
nigel, September 2011