I don't think that site or any of the others that calculate profitability are ever accurate. I could be wrong but I tried mining individual coins and it was no where near what those calculators were promising.
Yeah it is a little misleading. I'm pretty sure it is calculated on the real time values so it wont be realistic as mining and unloading takes time and by that time usually the market has changed. I usually get around the middle range of all the coins on this pool. It has been great recently though!
Yup, that's why a lot of the unexchanged was already locked in today... right now the price for DOGE on Cryptsy is pretty epic (vs where it was even a few hours ago), however, if it comes down later, then the whole pool earns less. They really should have an "average" profit calculator on that site(CoinWarz), as often a very volatile coin will be on top (and people will start mining it), only to drop to the bottom once people see it's on the top and start unloading.