How Many HPS

How many of these do I need for 2 - 6 plants(depends how many come out female).. and which lights 150 watt or 70 watt?

70 Watt HPS Floodlight

150 Watt HPS Floodlight

Also how much growing space do you think I will need without it getting to over heated?

Just get yourself a 400W HPS for 2 - 6 Plants, maybe 150w for just two but anymore than that I would recommend going with a 400W depending on your space etc.