I've started mining with one asic miner (333MHash) in october 16, now I have two, and third is on posting. I already have 0.03BTC, next 0.01BTC is on the way (~70%) I think with my ~1GHash, I will stop buying miners for a while.

By the way, if I cool the miners with a fan (i've  bought one yesterday) could they mining more effectively, or just increasing the life period?

greenemso
No, if you write it to /boot/cmdline.txt you don't need to do it again. It will start also with every boot.