First Time Using 600w Lights --- A couple questions

Ive only used 1000s in the past and its my first time using 600s.. How close can i place my 600s? and will one 400cfm fan be enough to cool two 600s?

thanks!!!!!!!!

If they're air-cooled hoods, you can get pretty damn close. My friend regularly flirts with 12 inches above canopy pulling a six-inch Vortex through three hoods. 18 inches is generally safe, though.