if i were you i would add perilite to your soil from now on. It will help to air up your medium, and air is what the roots need! When i grew is soil i had a 60/40 dirt/ perilite mix. its cheaper cause perilite cost almost nothing and its much better for your ladies. Good luck and dont water to much!
well i origannly planned to flower these out in the pc but my containers are a bit big , i dont have much money for a good fan for my bigger box that one is also missing a light setup.
Yeilds depend on tons of diffrent things,strain, nutes,light sources etc... In your situation a scrog sound perfect! you could fill that area up full of awesomness. Ive done grows in beer cups tons of times but was under the 1000 hps and id average maybe a half zip of so, but that was doing single spears? w/ a scrog and a few nice tops each im sure a zip per cup would be possible. Really depends on the strains!