Tent/vent/ ac setup questions

I am considering setting up a 4x8 tent with 2 600w HPS under cooltubes. I have a 6 inch inline fan and carbon filter but my main question is if it is a better idea to use an AC with one inline fan or use 1 fan for exhaust and one for lights. If I use the AC in the room can I use it for intake and outtake?

It's best to keep the lights on their own exhaust. Same for the carbon filter. If you ever add CO2, you'll need them separated anyway. You may want to consider using a different reflector (like the Radiant reflector by Hydrofarm). Like the Cool Tube, the Radiant is air cooled. The biggest plus of the Radiant reflector is that the aluminum reflective material is brushed (not hammered). This increases the actual reflectivity by about 10%.

You can see the Radiant reflector here: http://www.shop.gyostuff.com/Radiant-6-Air-Cool-Reflector-Unit-includes-lens-RD6AC.htm

As for the AC, try without it first. If the air outside the tent (the air that you'll be blowing through the lights) is cool enough, you may not need the AC.

Good luck. Keep us posted.

So how exactly would I run everything doing it that way? Wouldn't any odor get out from the lights exhaust?

Your lights should be on their own sealed exhaust system. If properly installed, you won't have any odor problems. See the attached pic to get an idea how to run your exhausts.