Arms is top dog for PvP, general spec build if you want to play 3s will be something like
Juggernaught
Second Wind
Disrupting Shout
Shockwave
Safeguard
Stormbolt
You can probably succeed with Bladestorm/Bloodbath to about 1800~ but people start learning how to outplay it and without stuns versus good players you do start to struggle.
Stat priority is pretty simple, 3% hit, 5-7% expertise to account for extra dodge and Nelf racial, as much as crit as you can, I tend to ignore anything below 180 pvp power, but naturally if you gem 320/480 crit you'll get the 60+ strength socket bonuses by default.
Rotation wise the simplest version is just;
build rage
use OP outside of CS
Use CS around 60-80 rage
Slam as much as possible, you can also use MS in CS if you're short of rage
Spread Deep Wounds (got buffed) using thunderclap wherever viable
Heroic Strike is practically useless now, I'd even hesitate to say with the amount slam hits that Execute is the same really... Overpower is quite nice considering it's un parry/dodge able and lowers the CD of MS
Good luck!