The answers to your questions depend highly on the arena bracket that you participate in (2v2, 3v3, 5v5), and what the rating of your team is.
The reasons are as follows:
1. Unbridled wrath is a mediocre talent for 2h warriors (since almost all arena warriors use some form of MS build). Your attacks are simply too slow for UW to proc enough times for it to be worthwhile in any way (i.e. enough rage to perform some other attack), whereas increasing the duration of your shouts by 50% may mean that you do not have to worry about reapplying that buff and wasting rage and a GCD.
2. The answer to this question depends highly on the makeup of your team, although I'd still tend to lean towards Commanding Shout. Everyone benefits from CS, whereas only melee will benefit from BS. Stam is king in arena, and a 1K HP buff is really nice.
Without knowing what arena you participate in and what your rating is, it's hard to say for sure what is better, but those are generally the guidelines that I would use.
-Camel