10/48/3 = the raid dps spec. end of story.
with the recent and the upcoming changes (MSD nerf, ice block for all specs), frost and arcane are falling more behind compared to fire in pve.
until you reach 164 hit rating, +hit is the best stat to get. that does not mean you should ignore all others. and once you get 164 +hit, you should keep stacking spelldamage, crit, spellhaste (not if you spam scorch) plus some stamina and int but that will mostly come with your gear improvements anyway.
you can do kara as frost, but later on you will just be slowing down your raid if you stay frost. i suggest switching to fire early on for two reasons:
- you can practice playing fire spec.
- you have time to adapt your gear to the spec.