As for 2 or 3 cells, that depends on the prop size you want to use, 2 cells for bigger props, 3 cells for smaller ones. That might seem backwards as you may be thinking that you would use a bigger battery to swing a bigger prop, the reason for small battery - big prop is the current involved and to reduce it.
One of the important bits of info about brushless motors is the number of turns that they are wound with, more turns = bigger prop, less current and lower rpm, less turns = smaller prop, more current and higher rpm.
I am guessing that your motor is 13 turns, so 8 x 4 or 9 x 5 on 3 cells or 10 x 5 on 2 cells.
For battery / prop size
http://www.flybrushless.com ( no login required) Find a Prop & Find a Motor from the menu bar.