Hello OverRide, yeah, five minute air exchange is what Ed Rosenthal taught us in class.
About the light, I don't know what you're willing to spend, but everyone here seems to be going LED. I have a little experience w/ those and it was expensive and not that great. If you are going for more light, the LEDs have some great penetration, the problem is they have a tendency to heat up quite a bit and that leads to failure of the components, not to mention heating up the girl's environment. If you're into building your own, you can control the quality of heat dissipation and I'm sure that would be better than what is available from manufacturers.
I do use T5s for my seedlings and clones. I veg and start my flower w/ my inda-gro420 and finish w/ my 600w hps. I've supplemented my inda-gro420 w/ a couple of 150w HPSs, that I had around, and that really improved my girls' productivity. That was before I got the big hood and 600w HPS.
Since you have a bigger footprint than I, a less expensive route could be a light rail. That would get you the coverage you'd like as well as the ability to get the light closer and more penetrating.
If you want to keep it simple go with the t5s. Use the 6500k lights for seedlings through veg. The truer whites and blues will help develop early development, growth and nodal spacing. Then start switching to the 2700k lights during flower. The more red light will help out with the flowering. I'm pretty sure you can get away w/ the 600w light all the way through, but if you want to get the most, out of your time as well as the girls' lives, get more coverage or power on that grow. Most importantly, enjoy the entire experience.
