yeah if you get these fans it's best to put two, one on each side of any odor control, one pushing, one pulling the air through.....
if it's a small cab using CFL's it'll work to keep the temps down.
just keep the exhaust up high, the intake down low.....
If you are using two fans, both should be pushing. If one is pushing and one is pulling, you arn't creating negative air pressure, and you arn't utilizing both fans.
If both fans are rated at 110 CFM, and one is pulling 110 CFM in while the other is pushing 110 CFM out, you are moving 110 CFM. On the other hand if you put both to push out, then you are moving 220 CFM out.
Also, go with CFL's, 150 hps in that small of a space will be a headache. For your first cab that space is small, just so you know. It's always easier to build a big cab, then try to trim down, rather than the other way around. But good luck, none the less.