I second the vote for the hood risers. You could also get a new front bumper, the risers are more a JDM thing though. It would be cheaper, but not really needed unless you've got a lot of mods that are making the engine work harder or hotter (turbo, Nitrious, supercharger, or an after-market race header)
I would only cut vents or buy a new vented hood for show only. Especially if you are stock.
I would get the cold air intake or the Short ram air intake and don't worry about venting the engine compartment.
You could run a 180 deg. thermostat and make sure to flush out your cooling system and refill with name brand stuff. Keeping up on maintainance will help the motor run cooler and better too.