PLD 3v3 spec - questionsFollow

I just spentt my lunch break on Arena Junkies. Between my crappy work PC and this being my first arena season I couldn't figure out what I wanted to know - help is appreciated. I currently play with two friends and our arena comp is currently Ret Pld, Unholy DK and Disc Priest. From what I understand Ret Pld is not what it used to be. I find my best controbutions are defensive any way. Maybe I suck, or maybe its just my gear, but I do not feel like a huge DPS threat. I'm considering a switch to Holy.

1. How much does or comp improve if I switch to holy and how would my friends best respec?
2. How much does or comp improve if I'm holy and the priest is swapped for a warrior?