mining on windows is nothing but headache and way too much work, with the number of riggs you are dealing with is a full time job and than some. the down time alone will eat up your profit quickly if i were you i would look into some linux distros like ethos smos.

i am a hobby miner IT guy myself and been testing mmpOS and i really like it it's been super stable for my AMD cards

Best of luck!

about your power cost, is it 10 cents or 1 cent?
most power companies in US charge extra premium after 1000KW or so, is yours a fixed amount?