Adds: assuming you mean the Shadows, HS Bahamut -> SS Shadow -> Brutal Swing/Provoke -> BB. You can also start with BB but it's slightly riskier due to the animation. Brutal Swing and Provoke are preventative measures to get snap aggro as quickly as your GCD allows. Alternatively, as long as TP permits (which it should) you can just OP -> Brutal, then continue with your BB combo. Each Shadow spawns in 60s intervals, so Infuriate will be up for each one. Your Wrath usage will be: Unchained on the first add, IB on the 2nd, Unchained on the 3rd. You should be able to fit in enough GCDs to build 5 Wrath before/slightly after Unchained wears off, which will give you a free IB on Bahamut. Storm's Path obviously takes priority if a non-Hallowed Flatten is coming up, though.
Gear: Parry is actually fairly worthless in this fight as OT and MT. MT gets more out of it b/c of Flatten and it used to be more valuable simply to min/max healer DPS, but at this point with this much free gear it really doesn't have a necessary effect to prioritize it over Crit/Det. You're basically going to be tanking Shadows for all of 10s per (Parry has very little value here due to you having most/all of your CDs up), then you're tanking a bunch during the add phase but again you'll have CDs up for this, especially as WAR since you've got IB to work with. 75% of the fight is just you hitting the boss as a DPS, so damage stats are pretty great here.
In terms of STR vs VIT accessories, it greatly depends on what your healers are comfortable with. If you're still progressing I'd recommend 10k-ish in Defiance as your only real HP check is surviving the Shadow's swipe, Death Sentence (potentially), and Akh Morns. You don't need as much HP as you'd think for that. I'm not actually sure how much SS you have, but if you have >380, I'd recommend changing things around a bit to at least meet that threshold as it's pretty important.
Sorry if I missed anything. Hope that helps!
