i have germinated seeds under 12/12 but they only yield 3-7 grams.. yield is very difficult if not impossible to guess

i dont think that a 4sq.ft space will yield 2-3 oz with cfl/fluoros

that is correct.. 1gal per foot of hieght

circ fans arent good enough, the plant needs fresh air so you need intake and exhaust on your cabinet... mylar is always a good idea for walls no matter what your setu looks like

nutes you need on any size grow.. .co2 you do not need.. and for such a small grow i think its overkill

even one plant will get stinky.. so a carbon filter or o3 generator is a must

i dunno what you mean carbonated water?? dont feed that to your plant... the roots need o2, the plant above the ground needs co2... proper ventilation / air exchange will provide enough co2 easily... and if you want to give the roots a boost, bury an airstone at the bottom of your pot to increase o2 to the roots