1) Math says about 55cc (2000cc/(4*9.1))
2) :/
3) fs9 heads are the same, apart from cams, check link for more info:
http://www.mazdas247.com/forum/showthread.php?123713157-FS-Engine-Revision-Cam-Specs
4) really depends on tune, cooling, performance, and use. Max is about ~250whp. But that is...