1st thought should be to Google 'convert watts to BTU'. Why does no one seem to know how to use search engines....
FWIW, BTU/hr=Watts x 3.4129
The CFM, fair question. Don't think there is any data on that. I believe the fans move 250CFM free-air but under load, pure guesswork. I'd ballpark it as around 150CFM
I looked up the specs of the Antminer fans, they output 220 CFM at 6000 rpm with no diff pressure. In practice there will be diff pressure across the miner so it should be somewhat less.