Hi there, if your looking for some Ret arena tips, I would be more than happy to share my 2 cents. As for talents;
Long Arm of the Law - Consistent Move Speed, key word being consistent and more reliable than the other two. Speed of light has a cooldown, so if you miss the window, it hurts and you never should be maintaing three hp long enough for pursuit to be too useful.
Fist of Justice - Straight and simple, best thing here. Rely on your partner to snare for you, and use this 30 second cd stun to your advantage.
Selfless Healer - Awesome talent for off healing your partner, 3 judgments and you can get crits of around 180k. Another reason why maintaing inquisition for the 30% crit is important. Even a 2 stack selfless healer proc is good on keeping you, or your partner alive.
Clemency - This one is relatively straightforward, 2 freedoms, 2 BOPs, 2 sacrifices (which purge all magic effects on your partner). Just awesome for more utility.
Holy Avenger - Arenas is all about burst and dropping someone as quick as you can mash keys on a keyboard. This talent provides you the most hp in a short time frame thus allowing you to send TVs into your opponent's face on a frequent basis during its duration. Also it helps provide a free 3 hp inquisition on one judgement.
Holy Prism - Awesome heal either way and available more often than the other two. Also if your sneaky, you can use it one yourself and pull a stealthy out with the damage.
As for your CD question, we still are stacking CDs for our best damage. Ret burst is absolutely reliant on Wings and Holy Avenger, so these are always popped together to maximize damage. Guardian is a huge cooldown that gives us massive strength, on a lengthy 5min cd, but is usually popped in arenas on that first burst phase. Usually, the offensive rotation is Guardian until you have around 10 stacks of the buff, Wings and Holy Avenger, and then damage.
As for getting locked out of the holy tree, you need to only be using selfless healer when you have at least two stacks. A one stack selfless healer is very easy to lockout and it would be just as beneficial to have your partner pop some defensives while you get off another judgement for a stronger heal.
General information for your arena experience as a Ret;
Get a partner that can peel for you or is a "tastier" target for your opponents. You don't want to be your enemy's focus as Rets die pretty quick under pressure. Your maximum potential comes from all of your utility and supporting your partner while using your burst in synch with theirs to down one person. Dont forget about things like giving freedom to your partner to help them against certain classes. I run with an arms warrior and when we play against something like a frost mage it really helps him out. Blessing of protection saves lives, and you can use it twice with clemency. Also, hand of sacrifice, as i mentioned before purges magic effects of your partner. You can save them out of a pesky deep freeze and take 30% of the damage they take for a short while. Also it should be noted that the damage from hand of sacrifice is magic damage, so divine protection reduces it.
Last thing i can think of is don't forget about concentration aura, it makes you immune to interrupts if you absolutely need to get off a heal. And the 20% magic damage reduction works for you and your partner, so its a win win.
Good Partners I have found so far (for 2s);
That's just my short list, though. I am finding more every time I play so it is bound to grow. Sorry this rant was so long. Hope I helped.