What will happen to our div's if power costs are higher than the amount of bitcoins? I don't want to pay on top of it to get overpriced div's at the end...

If the cost of power rises higher than the bonus amount, you need to cut Lab_Rat a check every week to help pay for power.
Lol. Don't remember that part in the contract -- either version.
I 'd guess operating expense runs somewhere around $3k a week. So, I'd guess that somewhere around $200/btc, there is no bonus, and lower ends up being Bad news. In the endgame, Zach would forego his comp, to see if btc snaps back. If it doesnt, then things start going dark, since electric bill couldnt be met. Theres potential that things get ugly quickly. But, btc is incredibly volatile. Its insane to do forecasts, since normal range corrections in either direction is massive.
It wasn't and isn't in the contract... Trolls gotta be trolls.
Your guess on operating expenses are pretty close, but slightly over after rent, power, internet, etc. Closer to $26-2700 and getting lower.
The only issue is the price is going down and diff going up at the same time. More power efficient hardware is on its way and there are some big plans for Q1/2015 to greatly reduce costs and increase hashrate.