C02 would be the way to go I would say. They are kinda spendy to set up but it will be worth it. Faster veggin, fatter flowers, and temps aren't so much of a problem. I have read that plants can do even better in higher temp with proper c02. Ventalation isn't so much of a probelm with c02. I fact to much ventalation can lower the c02 in the room. If you do run c02 would should have any fans you are using a a timer. That way you can have the fans on when the c02 is off. Air is lighter then c02, so the c02 will fall down to the floor quckily. So you should mount it somewhere above you plants.
As for your fans, air intake fans are kinda like pull fans to **** air in and the blow it out. The work really well for bring fresh air in. If you don't use c02, they could do the job for you. Bring fresh air(new c02) into the room. It will not work as well as c02 I wouldn't think. House fans will work to premote stem development, move air around, & lower temps. Their would be no need to cut a hole in the door if using one of these. You could just put it in the room. If you don't want to use a lot of spendy fans you could just open the door to your grow room, its small enough that might work.
As for odor a carbon filter would do the trick 6 pounds should be good. You can find a lot of filters that come with intake fans so they will pull the air in to filter it. Hope that helps:tokie: oh for some reason it stared out the word s*u*c*k in case you were wondering what the stared out word was. In way way ment to offend anyone.
