Elitist Jerks - [Help] Disc Priest in Arena

I started serious arena games late, at te end of Season 2. I was just grinding the petty 10 game points before because it was the only way to get a good healing weapon on my priest alt, who now is my pvp main.

I've been running Disc in arena since the talent changes. here is her current armory The World of Warcraft Armory

I was talking to a few other guildies about talents choices, and a few arguements arose:

1). Imp. Shield + Reflective Shield: I personally don't feel like it's needed because the damage reflected is so minor.

2). Focused Power: I fine it extremely useful when we need to burst down a pally or frost mage. But I was told that the spell has very bad dpm and it's not worth the mana to dispel iceblock since a iceblocked mage essentially CC'ed himself.

3). Imp. Healing: In my current gears with my current build, I think my mana is "ok". But I am sketical about dropping Imp Healing.

4). Usefulness of the new pvp trinket: I have the badges to get it but I I am not convined that it's all that useful. I can see myself wanting to use the trinketWhen I am being locked down or focused fired by warrior/rogue and taking alot of damage, in which case, when I do get a split second to cast anything, I would rather Fear or pop a shield or PoM or even Renew. The 1000 something HP won't really help (unless I am already down to very low on health) and it will drop back to 1HP when the effect is gone. Obviously there are good specific situations where you could use it (such as needing to heal yourself while bying slienced), but overall, is it that good?

Would like to see what others think on the above questions. Also, would appreciate if someone can give some talent builds for 2v2/3v3/5v5. (3v3 being most important).

Thanks in advance.