Growing from seed you will probably only get 4 females from 6 seeds so the space thing is less of an issue (you will cull the males in week 2 of flower). I think the proportions of that box are funky at best- tall and skinny is a tough way to grow plants, and the box might benefit greatly from the addition of tube side-lighting such as a couple 24" under-cabinet flouro fixtures.
For odor control, an 'odorsok' 4" model will fit right over the exhaust outlet. I don't know if the fan in that thing is burly enough to push air across a carbon filter matrix though.