1st Grow and New Grow Room!

i just bought a 4x4x7 ft grow tent. ive got a 600 watt hps light in there right now for flowering. ive got 2 plants right now that veged under cfls for about a month before switching to a MH bulb and finally the hps. im looking for a good fan that would pull enough air into the room to keep it at an optimum temp.... im probably looking at having to by an inline fan so what would be a good size or power? also, this is probably a really dumb question, but has anyone found a good way to block off the light that comes through the unused vents as much as possible? im gonna have some more questions as i go but for now thats all i can think of.

you need to change the air 3x/minute, 4x4x7x3=336cfm considering the inefficiency and curves i'd go for 400cfm. you can used curved duct painted black for blocking light, make smooth curves for good venting

ok so youre sayin for those other vents, just use some small amount of duct thats just not attached to anything?
i just want to make sure im gettin this right. im still a newb after all haha

I think you are talking about the passive intake holes, where there is just an opening to allow air in, you can use a curved duct and just tape it to the size of the hole to allow passive intake through it, place exhaust fan on other side of room to suck air through the curved pipe...

Alright thanks that's gonna help a lot. I'll give it a go and see how it works out for me