I don’t know about Callagadra because I haven’t tried it with this character, but about Crate it’s a yes, I did it. Some kiting is required btw, you cannot facetank it.
For crafting you have to aim to stun duration reduction until cap, then %physique if you want some extra health / DA. Or you can even craft at Gaius Ember if you want extra crit damage. I personally went for a mix of stun duration and physique.
If you feel lacking about the sustain part you can incorporate Bat in the setup and link twin fangs to pox, removing Imp (aetherfire) and modifying the devotion path to match requirements.
If you want more consistent DA numbers you can use two ravager’s eyes on both wand and codex.
Once you get used to it, the gameplay is more of a MoE + Hourglass work (via Doom Bolt) to prevent dangerous spikes from nemesis waves / super bosses. Don’t even try to facetank Reaper, Kaisan, Father Kymon or IM unless you have mirror up. Trash mobs are trash, with the slow effect from curse of frailty they don’t even get to you before they are dead.
EDIT: when I talk about bosses / nemesis, I am referring to crucible and shattered realm. Main campaign is super trivial, the only exception being Morgoneth and his massive DA debuff. Don’t facetank him or you’ll get critted into oblivion.