What goes wrong?

[Tenet]

In my experience, I think not using all your defensive cooldowns at once is important when fighting elites. For example, not popping BoH, Serenity, and Blinding Flash all at once. Instead, I try to use one and do some damage, then another and a bit more damage, etc. and kite until they come off CD.

My build is pretty similar to yours - FoT instead of CW, no ally, and no longer use BoH since it is kind of paltry when you have ~35k health pool. IMO FoT interrupt stops more damage than the debuffs CW applies, in addition to being much faster. With Thunderclap, you won't have trouble catching casters, plus while it won't break jailer, if another target is close enough it will still teleport to them, which can be enough to get you out of desecrate, poison, etc. I also really like SSS with Sudden Assault. It's great for mobility and a bit of damage. Finally, Sweeping Wind/Bladestorm is pretty glorious - easily the most damage/spirit ability we have - providing constant, high damage to everything around you. The trick is recognizing how to keep it from falling off when you have to kite (FoT/Thunderclap helps a lot with this).

[Armor_Biff]

Until I suddenly run into a bad champion group: like nightmare + frozen + arcane. Or desecration + jailer (and that together with a 'charge' type of monster that you have to evade or it 1 hits you). or -currently- waller + molten + shielding.

It always goes the same way: I get cc + damaged when stuck, so fast I need to use all my spells (heal + serenity). However before those spells are off cooldown I get cced once again.

I recognize this all too well. I've died 3 times in hell so far (in act 2 now) and always because of a waller + elemental combo. They corner me so I cant move, and then burn me from below with either poison or fire. All spells and potion are of course in cooldown at that point. I have not found any effective way to counter that kind of combo yet. Inferno will be tons of fun.