A few things I've never been quite clear on..

I've always had some unknowns about fans.. so a few questions -

What actually determines if the fan in question is an intake or an exhaust? Just its placement in the case? The direction it spins (if so, how do you know if a fan is set as an intake, or as an exhaust)?

What happens if you flip a fan around/put it in backwards? Will it just blow air in the opposite direction? How do you really tell which way a fan should be mounted (which side pointing where)? Does it matter?

How can you tell if the fans inside your case are working against each other/producing conflicting airflow/etc?

If you have a massive HSF on your cpu that blows huge amounts of air around, and smaller/less powerful exhaust and intake case fans.. will that create turbulence inside the case and make the case temps higher due to the inability of the exhaust fans to keep up with expelling the air the HSF is blowing around?

The reason I ask the last one is cause I just put a Vantec Tornado on my CPU, and while my CPU temp dropped by ~9C.. my case temp actually went up by ~2C.

Anyways, I think that's all for now.. may think of more later.

Thanks for any answers.

What actually determines if the fan in question is an intake or an exhaust? Just its placement in the case? The direction it spins (if so, how do you know if a fan is set as an intake, or as an exhaust)?

if it's blowing into the case it's an intake, and if it's blowing out of the case, it's an exhaust. ;)

What happens if you flip a fan around/put it in backwards? Will it just blow air in the opposite direction?

yes.

How do you really tell which way a fan should be mounted (which side pointing where)? Does it matter?

some (maybe most) fans will have little arrows on the casing showing you which way the fan blows. or if it's plugged in, you can usually tell just from feeling the airflow.

How can you tell if the fans inside your case are working against each other/producing conflicting airflow/etc?

good question. i think monitoring your temperatures will be the biggest clue about that, as you discovered from your new tornado.

The reason I ask the last one is cause I just put a Vantec Tornado on my CPU, and while my CPU temp dropped by ~9C.. my case temp actually went up by ~2C.

i'd say that's a pretty good trade off. as long as the case temps are not really high and your hard drives and other components are staying cool, i'd be pretty happy with that result. if it's an adjustable fan or if you have a fan controller, you might be able to take a few rpms off the HSF and cool down the case a few degrees without raising your cpu temp that much.