2 sets? does that mean 2 lights or 2 pairs of lights? Either way that's not going to be enough light. You need a bare ass minimum of 50watts per square foot. Even at 4x 40watt 4 foot bulbs that is only 160 watts total and only 40 watts per square foot, not enough. I'd double that atleast, if I were you. Also it's a good idea to alternate one cool light and one warm light so that your plants get a more balanced spectrum.
As for how many plants you could grow in there I'd say no more than 4 to full growth. So you could start off vegging 10 and giving room for death and males you should end up with 4 or 5 females to flower. Sorry to say if you ended up with more than 4 you'll have to choose the best 4. If you tried to crowd it you'd end up with less smoke in the end.
Also, do you have a seperate room that you are going to keep the mothers in? or a seperate room for flowering? If not then you can't really do the whole mother for clones thing, because when you go to flower your plants your mothers would flower too and not be mothers anymore.
Hope that helps and good luck.