Fighting the shit out of temps myself, hoping sealing up the second hood will help, that and rebuilding the fucking swamp cooler.
Anyhow as far as cooling goes intake air temp is everything (well an air cooled hood goes a long ways too), but if you are pulling in 85 degree air, you are never going to get it below that. So clearly when temps are 100+ degrees as they are now, intaking from anywhere not cooled in one way or another is going to play hell.
I have always gone with more is better in air flow numbers, i probably run 1500 true cfm when lights are on. This way i can skip cooling the room separate from the rest of the house, or adding co2, as a family of 4 in a fairly small house produces a fair amount of co2 naturally. Down fall to the huge air movement numbers is having a big enough carbon filter to keep up, but this is the one place to never skimp, i know my $250 couldn't have been spent in any better way, saved me more than you (or I) will ever know.