Grow Cabinet Help Please!!!

I am going to start my first serious grow soon and need some help. My grow cabinet will be 30" x 36" x 60". I am thinking about having a 250w MH for veg, in a separate cabinet of course, and a 400w HPS with digital balast for flower. I want to have a 4" inline fan for ventilation and a DIY carbon filter. This cabinet will be in a small closet, roughly 5' x 4' x 9', in my room. I live with my sister and stealth is number one. She doesn't go in my room at all and my closet can be closed. The lights will probably be from htgsupply.com. I'm not sure about the inline fan yet. I need a quiet one, but strong enough to cool my cabinet. Another big thing is heat. Being that it's in the closet, it gets pretty warm. And South Carolina summers don't help. So I also need something to keep my closet cool. The only ventilation source is the door, and I don't want all the heat from the lights going into my room. So if anyone has any ways to cool everything down, it would be a huge help.