The rotation on noxxic is kinda simplified, try recreating the action priority from simcraft.
1. There's nothing really to be done that can help with this beyond practising and playing the Nameplates on,
2. When to AoE will depend a lot on your guild's strategies for each encounter and they tend to vary quite a lot between guilds. As a general rule of thumb use sweeping strikes if you have a second target that you want to die, replacing a Slam with a TC every 15 seconds or (its better to do it too often than not enough) on 5 or more targets Replace Slam entirely with TC and Whirlwind.
Arms is pretty decent I've played it till 2/13 HC ~523 ilvl with the vp upgrades boosting the ilvl up to 530 fury pulled just too much ahead, but until then enjoy arms
The noxxic rotation is really really basic and missing quite a bit of the little things to do good dps. 82k sounds pretty low looking at your gear I'd expect 120k-130k maybe like 100-110k on the dummy you must be doing something wrong also why aren't you using any set bonuses? The T14/T15 2set are both pretty strong and the T15 4set is awesome.
CS if the debuff isn't up or 0.5 sec left
execute if CS is up or you have 90+ rage
OP the right amount
During CS you want to use 3xOP and on the last 0.5 sec of the debuff use MS>CS>slam, never use OP on the last 0.5 sec as other abilities hit harder. If CS isn't up you don't have to save any taste for blood stacks but go MS-OP-slam-OP-MS don't go MS-OP-OP-slam-MS since when CS procs on the last gcd before MS you'll have 1 taste of blood proc left if you use the first rotation.
I've been using a macro with bloodbath+dragonroar+skullbanner and another macro with CS+recklessness. Going MS-OP-DR-CS-MS-OPx3-MS and then either CS if it procced or the regular OP/slam stuff. If you have the T15 4set slam will overtake OP resulting in MS-OP-DR-CS-MS-3slam-MS-slam/CS.
Berserker rage whenever enrage falls off. HS during CS without ragestarving yourself or if you get to 100-110 rage, if you almost ragecap you probably didn't HS enough on the previous CS. Make sure to use your dragonroar every minute and reck every 3 minutes delaying 5-8 secs tops for CS.
I use the sweeping strike glyph a lot with the interrupt, heroic leap or enraged speed as third. For example council stay on Sul interrupt him every 12 secs for 6% free dps and cleave the frostking the whole time with sweeping strikes.
1. Targeting mobs with your mouse(keybinds and thumbpad for rotation) or switch with tab. Not sure what the problem is I usually watch and follow the tank as the mobs are running after him. Tidy plates is a nice addon might help if you have trouble getting the right mob.
2. For 2 mobs just single target with sweeping strikes for 3-4 mobs sweeping strikes but weave in some thunderclaps every ~15 secs to get deep wounds on everything for 4-5+ mobs go full aoe MS>Tc if deep wounds isn't up>whirlwind>shout if not enough rage.
Looking at your progress you want to single target with sweeping strike on council(TC when Kaz charges close), single target+sweeping strike the important mobs on horridon while weaving in some thunderclaps if enough mobs in range and on tortos you want to save a little rage and then go full out aoe when the tank got the bats with TC-DR-WW.
Bladestorm is viable on tortos and lei shen just make sure you don't forget to use bloodbath then as you won't have it macroed into dragonroar any more.
Also unless the mob you're sweeping to is going to die from the hit, don't use cleave, A swept HS does about damage, thought its not a 50/50 split mor eof a 66/33 split focuses on your primary target. I know in previous expansions a swept cleave hit for a totaly of 4 hits (6 if glyphed), but in moP Cleave no longer benefits from seeping strikes.