May I ask for some advice?

Im a first time closet grower. I have plenty of space, im only growing 2 or 3 plants tops. I have a ebb and flow system, ph down, 3 part Advanced Nutrients GROW MICRO BLOOM, 250 watt hps and MH lighting, I have a couple of fans in there too, seems to keep the temp at about 78 - 82 pretty well. Ive got everything but a ppm meter and a vent to the attic.
I was hoping to get some veteran advice on anything really, id like to do this right the first time. Is it manditory that I install a vent to the attic, or have a ppm meter, and how often should I feed the plants?
Any help or advice anyone could give me would be awsome. Ive done a lot of homework and money spending to make this happen, but nothing beats experiance. Thanks guys.

PPM meter is mandatory if you want to be successful and plan on optimizing your yields.
You can get by without it, but your results will reflect that. You should also look into
a PH pen as this is vital too.

A vent to the attic is not necessary. What is recommended though is that you
move out old air from your room and pull in the new air as stagnant air will diminish
your results as well.

Here's a really great read on dialing in your grow room conditions:
http://urbangardenmagazine.com/2010/04/hydroponic-recirculation-basics-part-3/

Yeah id set up an exast fan keep pulling air out if its eazy to send the air to your attic than go for it ...it should also keep the smell up there in your attic and out of your house .....also Mix up your res with nuits all the time every time your plants get water it should have nuitrents in there

Use a carbon filter and keep the smell in the carbon, not in your attack. You can vent through the carbon filter to anywhere you want including your atic. If you vent back into your house less pressure will build up so the fan will move more cfm's which I recommend, especially since fall is coming soon it will help the heat a bit and as an added bonus if you set it up right it will be constantly circulating the air in your whole house and filting it. This keeps your whole house fresh which is good for a smoker.

Peace,
IF

Thanks for the tips everyone, I appriciate it. Does anyone know the the nutes ratios for feeding? I here I should cut the amount allmost in half, but still not sure. Thanks again guys.