Help with first set up plans.

So I am about to start my first set up. I've been doing some reading and acquired some good seeds. I am thinking of doing a small cabinet style set up with 2-4 plants, and I'm on a budget. Space will be small. My few questions are:
1. Should 150w HPS work fine or will I need 250w?
2. For cooling/air, I was planning on 1 inside circ. fan, 1-2 exhaust fan on top, and 1-2 intake fan at bottom, is this enough?
3. Will smell be a problem I should worry bout, or should i get carbon scrubber?
4. And plan on covering with mylar or foylon.

get a scrubber

get a 250 hps.....

lets just say you get 4 females, there's no way you could keep them going really well and let them grow to a good size.

make a carbon scrubber