You still need exhaust fans as you need to recycle the the air within the room, and even that LED produces less heat there is still heat coming from the lamps, just not as much. I'm using advanced LED lights and they have thus been pretty darn good, I would recommended taking a look at those lights. they are a little more on the expensive side, but you have to pay the premium if you want to go the LED route. On their web page you can see size charts which states how large a coverage area each individal light can handle. You could even just have multiple lights and daisy chain them together as the lights provide this option as well as the cables.
As for smell, I would stay away from Ozone generation as there have been a few health articles out there that say it causes lung problems as breathing in pure ozone could be harm full.
Your best bet is to go with a inline fan with a carbon scrubber. Take a look at some of the Can Filters and their fans... Any duct work you can grab from Home depot and vent it out side. Be sure to look at the stats of the scrubber and pair the fan and scrubber together. Look at fan How To's to determine your cubic feet and how often you should recycle the air within your environment and make sure that your scrubber can handle the CFM required to accomplish this.
Alot of information but I hope it helps... I'm a noob as well but been researching alot of stuff on the site!
