How many want to play co-op mode ?
My FPS skill is not good , so I want to play co-op mode to enjoy this game play more and more.
Steam version Doom 3 BFG edition will support this game type ?

No coop on PC. The original DOOM 3 has it either on Xbox or on PC with a third party mod. Console versions have coop in DOOM and DOOM II, not in DOOM 3.