4x2 tent with vents need your help

I have a 4x2 tent http://www.htgsupply.com/viewproduct.asp?productID=53389 that I'm putting a 4 inch carbon filter http://www.htgsupply.com/viewproduct.asp?productID=52531 on at the top. I need to know if I need a a fan to bring air into the tent or if I can just open a flap at the bottom. And how good do carbon filters work?

u can just use a fan to exhaust thats what im doing and leave the flaps open

will it smell if I leave some flaps open?

you know it might smell a little so maybe tape the bottoms flaps closed and there is a vent hole you could open or put a small cheap duct booster on there but i think the negative pressure would stop the smell from seeping out

IF i buy that tent is it going to be high enough to be used as a veg room ? could i have a mother plant and clones in there ?

ok i'm going to be completely honest with you here...
check out my cab grow in my sig...

I just recently paid a visit to htg supply and picked up a truck load at almost 2,000$ a few things on my grocery list were 4 6" inline blowers with 6" charcoal filter combos... the carcoal filters are amazing... they eliminated smell in my house and cab 100% very very good quality, and the blowers move so much air it's unreal... the tents on the other hand are junk... I had 2 4x4 tents on my list and when I got down there I asked to see one in person so they began to set one up... well after an hour of setting it up it was finally up... the tent itself was crooked and very very very poor quality... they hung one of their easy cool 6 fixtures and just from the weight of the light it looked like it was going to cave in... it's like a tin type tube for framing I was very quickly un satisfied... here's my suggestion they do sell rolls of white poly that is 6mils thick very good durable stuff... go out and buy some 2x3 studs and frame your grow room then buy some white poly good price on a 150' roll and make your own enclosure.... honestly ...
I do not recomend the tents they are junk...

you i have to agree with him on this one the tent isnt quality i just figured you were set on the tent but it very cheap i use mine for mother plants and clones but it very crowded and not that nice honestly it works if i had more space i would have made a different choice but i didnt have the space only downsite to making your own tent is usually once its made thats it cant tear it down and make it again an hour later if you might want a bigger tent for really not much more money this is a real quality tent http://www.growlightexpress.com/grow-enclosures-tents-32/sun-hut-silver-lg-2x4-142.html i have this one and it really is great i think its better than the dark rooms systems but thats my opinon also the pic shown is an old pic the new one has a bunk of holes that work as a sock or flange but only 6in holes no 4 in i think and they have great cusomer serive