It will be very difficulty to find btc mining profitable at this stage, no matter you buy hardware now, make a pre-order on hardware or buy some cloud hashrate...
i found an hour of 180 gh/s for 8 usd.all calcs calculate in months not hours.So I dont know if this is profitable.(How fast does difficulty change? i know its every 2016 blocks but cudnt find more info)
what is the best pool?(according to chart: paypershare is best?)
A black averages ~10 minutes So 2016*10=20160 Minutes 3360 Hours 140 Days That doesnt Sound right but thats the math for the numbers you just gave