Crit or haste?

[:1]So I've leveled my first mage (should be 85 early next week), and absolutely love fire. Ton of fun, exciting procs and I'm doing 10k dps at 82 and 83 in dungeons. I have several 85s so I know what to do first to get gear (Thrall quest, Hyjal for head enchant, I'm a scribe so I don't need shoulders, thank god I'm so sick of Deepholm), but my question is - crit or haste for fire?

Haste improves DoTs, speed for pyroblast and fireball, but crit of course gives hot streak and just does tons of damage. Also, what would be the best JP piece to buy upon hitting 85? Should I even try for the legendary at this point or will it take too long?

Final question - for PvP as fire, should I spec into shatter?
There's a certain point for both. You don't just ditch one and go all out in the other. I believe you get enough haste to have Fireball at 1.5 seconds with TW on and then just do crit for the rest.

I'm not entirely sure, though. I haven't played my mage in a while.