I wouldn’t recommend fort def/res unless it’s your only premium a-slot. Stance skills are definitely better, the power budget isn’t wasted on player phase bulk that you probably don’t need and you don’t sacrifice atk, which is still important. Fortress skills also make it harder to chill soak, you can achieve more stats if you went for stances and soaked the chills.
As mentioned, you WANT DC. There’s no point in running a melee tank without DC, especially since most threats in AR are ranged.
Finally, Pale Breath is better with this build. Running both a joint AND a solo condition feels horrible because you can’t be adjacent, neither can you be completely solo without missing out on something. Either you run a smoke and Blackfire Breath, or Pale Breath with that build and have a support bring atk debuffs.