The link above can answer all the questions you pose.
In short, you shouldn't worry about threat stats much anymore, and until you have full CTC you are going to be stacking mastery.
I have to say this is correct if you're raiding and running with guildies/friends who dps and know how to control threat however the reality in 5 mans these days especially ZA/ZG is that the burst dps from geared hunters, mages, dks especially, means you want some threat stats of you're going to be farming. I found my pally while not needing hit cap by any means, did much better with threat when the expertise was around 20-23.
My DK was fine tanking with 0 hit and 22 exp just from gear; although I did move him up to around 5.5% hit since missing a Death Strike in raid was happening too often so I was losing a shield on every DS miss (plus my DS has been critting for 90k+ and that's pretty fun).
My warrior I had to get to around 6% hit since at 1% all it did was miss, miss, miss so on AoE packs Rend wasn't getting passed around.
Don't stack stam; although since I mainly heal these days I thinking that a stam set for FL is not a bad thing based on the damage I've seen so far.
You don't really need a "Stamina set" for firelands, the only really hard hitting boss is Baleroc, and he buffs your health far more than any amount of stamina gemming and enchanting could hope to achieve.
Full CTC is the target, and is manageable in 359/378 gear with two mastery trinkets, in mostly 378 you can get away with a single mastery trinket.
The gems are fine, although I would change the 60 stamina one to a puissant emerald. Enchants are also fine.
Glyphs look ok, be sure to change the HotR glyph to Crusader Strike for single target tanking.
Instructions on how to do the rotation/priority can be found in my tanking guide (linked in my signature). I also won't bite your head off if you ask a question in the thread like they sometimes do on EJ