I am in the process of finishing my basement, about 800 sq ft consisting of a bedroom, bathroom, and rec room. There are three existing heating vents, one in the bedroom and two in the rec room. I am thinking of adding a vent in the bathroom and another in the rec room near a window. This is heating only, does it sound adequate? Do I need to add cold air returns? Perhaps one in the bedroom and a second in the rec room?

Thanks,
-John

I don't have that much experience, but I think a vent in each room should work. You do need return vents. If the air can't flow out of the room, it won't flow into it either. If you are not up on code for arc fault breakers for bedrooms and GFIC for the bath, better post on electrical and lighting.

If you are installing a bedroom in the basement, it will require an egress window (http://www.ezhangdoor.com/installing-an-egress-window-well) to comply with building code (http://www.ezhangdoor.com/building-codes-international-door-installing). This is a means of escape in case of fire.