Advice Needed + Questions

[Eraser]

Hey Guys,
I've been reading this forum a fair bit, and the advice that is given is really quite good.So I'm thinking what the hell, any advice for me? I'm from a 10m only guild, except we occasionally down 25m FL.

The World of Warcraft Armory

Now for the questions
I have 3 pieces of T8 but only using one atm, the pieces I would use but don't have are shoulders and chest, should I change this?
Is Shiver (from hodir hard mode) better Titanguard?
The major problem I have is with initial threat, not against dps but other tanks mind, so if I may ask what do I use for initial contact, atm I use charge and SS but then I usually have to wait for rage before anything else. Is this the most efficient?
Lastly, is there any tricks that you know of for tanking that aren't obvious? (For Example: Using shattering throw in certain phases, or resillience to hit the def cap)

Edit:
How important is attack power in terms of threat as well?
How much tps should I be doing in my gear?

Thanks for you time.