Parts of a conversation from one of the top raiding mages on my server:

The theoretical min/max DPS for you does depend on the gear you have. Frostfire specs were optimal at early levels of Naxx gearing, and before Blizz fixed Torment the Weak to work on Thunderclap and other combat slows. At high levels of T7 gear, 57/3/11 arcane theoretically outpaces frostfire, and 18/53/0 deep fire also outpaces frostfire (assuming you can get enough hit rating on gear).

With arcane, it is definitely theoretical... Arcane specs take a lot of planning to play well. You need to know how long a fight is going to be and adjust your spell rotation accordingly to max your damage and ensure good mana longevity so you can last for the entire fight without going OOM. Most mages either can't plan well or don't put the time into it to do it right.

That said, if you do a fair amount of PVP, arcane is probably a better option than frostfire. Cast times are just too long with frostfire to be terribly effective. Arcane has more instants and short-cast burst damage.

Arcane is also very fun to play, but at the same time you need to be very engaged in it. Managing your AB buff stack with procs and stuff is a real challenge. But once you get the hang of it it's fun as h311.

Lastly, you always want at least 1 fire mage in a raid for scorch for optimal raid dps. The personal dps difference between arcane and fire or frostfire will never outweigh the raid dps of 10% crit. This will be easier in 3.1 when the crit debuff is nerfed and warlocks get the 5% crit passively from shadowbolts.

For rotations, you just have to develop a feel for how much mana you can burn given the length of the fight.

Here is a nice table of DPS/DPM tradeoffs for the various rotations.

Generally, the best standard rotation for mana conservation is:
Arc Blast, Arc Blast, Arc Barrage
OR if Missile Barrage procs during that, you change it to
Arc Blast, Arc Blast, Arc Blast, Arc Missiles

Never wait to cast a spell, but when you see MB proc, get that AB3MBAM fired off.

Also, don't change your spell choice based on clearcast or potency. It's not worth messing up the rotation.

When you fire all your cooldowns, you use a burn rotation:
AB spam, when MB procs use AM at a 3 stack of AB

You can get through 20 seconds of AB spam pretty easily. The MB procs will reset the AB buff enough to keep some of your mana. But if you're unlucky with MB procs you can fire a ABarr in the middle to reset the buff if you're worried about mana.

PVP is tough... generally speaking, I run around firing off arc barrage on every cooldown and channeling missiles when missile barrage procs. Depending on the class you can sometimes pop your cooldowns and ramp up AB spam to take someone out.

In BGs, I tend to try to hang back and use a AB-Abarr-AB-Abarr, with arc missiles on MB proc.