http://www.wowarmory.com/character-s...hal&cn=Krimlin

My main spec is a tank but I've recently joined a guild where MT and OT are set so I gotta work my way into raids with DPS.
I've only been playing 4 months and have little raid experience but have been building everything up with triumph emblems.

I know my hit is at least 8%.
My Armor Penetration needs definite help. I have gotten mats for +20 ArP gems and am going to socket them into everything. Should Armor penetration been my main focus until i can get soft cap? I know I should get trinkets that help me hit 100% armor penetration, I've been doing FoS daily to get scorpion trinket.
Should I worry about meeting all the needs of a meta headgear gem?
Which gem should I get?

Any advice on the best enchanting for my weapons? Does berserking only effect 1 handed weapons? If thats true should I just get Massacre for both weapons?

Should I get Dexterous Brightstone Ring or Bloodshed Band?
thanks for any advice. very much appreciated