- can i connect 3 bfl devices into one raspberry pi?
Yes, you can. I connected 2 jallies to my RaspPi
- can i use non powered usb hub for 3 of them?
Yes, you can. I'm using non-powered USB for the 2 jallies
- will cpu handle the load? therefore should i consider active cooling & heatsinks?
Yes, but I suggest you to find a 1.2A micro USB charger (I used apple iPhone4 charger which is 1A with a micro USB cable) if you are using a Rev B RaspPi. I don't know if you can use that 1.5A adapter because the specifications says 850mA to 1200mA
- which linux OS should i get & how much sd card space do i need for it? - im windows person.
It's called Raspbian, based on Debian OS. I guess this is the only OS working for RaspPi... (I didn't research on other OS), Min size for SD card is 4GB but I can only find 8GB in the shops here...
- it will not have screen or input devices connected so can i run team viewer for remote management?
I suggest you have a RCA connecter, a TV with RCA input, USB keyboard (USB mouse optional) ready when you are setting up the RaspPi. This is only applicable on first setup. After that you should be able to use TightVNC to manage it. (if you use the guide i linked below)
I suggest you go thru this guide that is created by BFL forumers (I personally also use this guide to setup my Pi)
http://goo.gl/z5IQRLast but not least, show us some pics of your BFL miners