a 250w HPS should cover a 3x3 room. one would do fine for what you are working with. hang it on some chains or something so you can lower and raise it as needed.

as far as the setup now, are those in a box or something? if not, i would suggest you use a cardboard box or something to build a little seedling box. that way you can maximize the ligth that you do have available. also do you have a fan blowing on them? try to get them fresh air.

it's looking good though.

-shake


edit: what are your goals with this project?