Crammed Growbox w/CFL... And NooBie!

Hi all, I am gathering some info in the hypotheis of growing a small plant for personal use.
I am new to this, and I have to start with the lowest possibile budget, so I'll try and do with what I have.
I have a box 15"x15"x28". My idea is to use ~100W of CFL.
I plan to seed 3-4 plants in small pots, then as soon as i am able to somewhat determine sex, keep only a female. I will then use about 11"x11"x11" pot for the last stage. That'll give me around 14-15" inches of growth. Of course i plan to LST, no other way.

Now for the questions:
Suppose I want to grow a male once, just to stock on seeds, can I fit two plants in there at some point, while not expecting any smokeable yield?
I guess i will do like about 6 weeks of vegetative and then go 12/12, is this correct? Is there a chance i'll be able to see preflowers by then, or at least before the final re-potting? Or else, maybe I can do a microbox in an upper corner and pre-flower? Is like, 15" space enough for preflowering?

And, most important: CFL's. I own 4 over the counter CFL, 20W eack, 2 with temp 4000K and two stating 3000K. They say they go around 1200lumens each. I was planning to buy one or two 24W possibile in the higher spectrum or white, and efficient. Is this ok for the full cycle? I am planning to mylar-ize everything of course.

Is a fan always necessary? Weather's not too hot, its about 60F now but will rise soon, I was planning on installing a 5" or 3" PC fan if needed.

Ok before telling me that it's a worthless effort, let me point out that I wouldn't expect a high yield. As soon as i get 8-10g smokeable out of this I'll be the happiest human on earth (even 6 would be great for a start) :)

THANKS TO EVERYONE who'll be so kind to shine some light on my doubts. ANY opinion and suggestion on how to proceed would be very welcome.

MW