[How do I control the height of a plant from a random seed? ] the same way you control the heigth of a $10,000.00 seed, you flower your girl knowing she is going to grow APPROXIMATLY another 1/3 to 1/2 whatever her height is at the flip. A 12" plant will usually go to 18" to 24" when finished her strech.

[I gonna consider buying HID lights for vegging and HPS for flowering. ] High Intensity Discharge, and High pressure Sodium is the same thing...as well a MH or Metal Halide. I would recomend, a floro set up for early veg, germination stages, and then to power veg HPS/MH combo. I'm a firm believer in combo lighting.

[ I just looking for a quick harvest] No such thing man.
Look, if your going to risk your freedom, your future, possible jail time, and complete loss of college loans and whatnot...I think you should do yourself a favor, read as someone above suggested, ever facet of growing, building, and maintaining a grow. Then make a detailed plan of how much product you need and tripple that, now build your set up to provide you with that amount in mind.

Doing a grow halfassed, is inviting disaster! At best a waste of time, resources. At worst, you can be bunking with Bubba!!

Last but not least, TELL NO ONE!