Hi.

To start with the smell.
A charcoal filter is not a big investment ant it filters 100% of the smell as far as I can tell here.

I dont ventilate straight to the outside either and I live in an appartment in a major city. My ventillation goes into the tent close to the floor passivelly then throgh the filter hanging at the roof of the tent---cooltube with 600W HPS in it---fan---out the top of the tent. Close to the roof of the room the tent is in there is a ventillation in my appartment that takes the air 4 stories up to the roof but I don't force feed this vent as I would create an overpressure in the duct then that might press air into other peoples apartments if my house's vent stops working for some reason.
This setup works flawlessly and is totally smell free.

About the lights it depends a bit. If u have white walls or even mylar walls I'd go with the 600W as one light is easier to handle than many and even though light has to be further away from plants it still produces a LOT of light.
But ye, I dont know what kind of area you are trying to light up etc so in the end you have to come up with a solution that fits your needs.
If you are using a cooltube you dont have to keep the light that far from the plants anyway even with a 600W hps.

Puffzter