Get a 6" centrifugal fan for your active exhaust and dial it down so that it's not blowing at full speed. That makes it a little quieter and if you need the extra fan power you'll have it right there. I'd also at least consider a cooltube or some other air-cooled hood for your HPS light, they really help control heat in enclosed areas. A nice alternative to a standard cooltube is this reflector:

http://www.bghydro.com/BGH/Itemdesc....LRECB6&eq=&Tp=

That also has a 6" diameter, and so would match a 6" fan without needing any reducers. Not cheap, but good reflectors last basically forever, so it's a good investment. I have both a real cooltube and that Cool Breeze and I like them both, but I'll give the nod to the Cool Breeze because it distributes light better. It is a little bigger than a standard cooltube, but you have room.

With a 6" fan for exhaust, you wouldn't really need any intake fans, just use passive intakes, and a small oscillating fan in each of the grow areas to keep the air well-circulated and to strengthen stems. You'll have plenty of light for veg; I don't even think you need as much as you're planning, but more is better.

All-in-all, sounds like you have a good plan to me. It's basically what I do too, except that I made separate small veg boxes so I wouldn't have to deal with lightleak probs between veg and flower chambers, or worry about a complex air circulation environment.