designing new room and need help

I'm building a 8'x11.5' flower room. I want to to cool the lights for a sealed room and eventually add Co2. I was either thinking for running four 1000 watt hps in htg big daddy 8" hoods or 6 600w(3hps 3mh) stagered. What do you think is better? Oh and one more question, should I be using outside air to cool my lights if I plan on exhausting back outside. Thank u for ur time

if you pull air from outside and exhaust back out the seals need to be perfect in the hoods or you will leak c02.
whats the ambient air temperature from outside?
how will you be cooling the room?

4 1000 hps

outside air as intake and exhaust in a closed loop, regardless of air temps outside

full blast exhaust for light loop in high temps, variac for low outside temps