Help For New Set Up Sog

Hi guys im going to have some free space and i would like to set up a Perpetual sea of green. 

I need some help deciding some stuff.

First how much space should i use for appx 20 plants max (Veg/Flow).

What lights shouls i get. Is it ok CFL'S? I was considering 400watt MH for know.

Which size of pots should i choose for weed not getting over 120cm?
 
Appx how many plants would be ok to harvest each time. 

Thanks for your help. This is my first serous grow so help me please. Good vibes. Thanks.