The closet I'm growing in is about 5x6 and is connected to my bathroom. I have no way to seal it since there is no door, I have no vent system except for a box fan blowing out of the room and an ionizer fan blowing underneath the light gently.

First question, how can I sell the room and whats the cheapest way I could vent it?

Second question would be how many plants can I flower under a 400watt HPS/MH light?

Also how much growth should I allow before re-potting my plants?

Thanks man!