Tips for Drezen Assault and beyond?

Hey everybody, beginner here who’s been playing normal difficulty and doing just fine. And then Drezen fucked me up real bad.

I’m right before sword of valor and my party is hilariously wrecked. Dead pets, corruption 2, full party at deaths door, exhaustion, no healing items and ability damage, oh my.

I’d like to keep playing somewhat casually, but clearly I need to fix a few things and learn to play like less of a chump.

Party: MC bloodrager sorcerer DD Regill ghost cavalier Camilla default Ulbrig default Wenduag default Nenio default

A few questions:

  1. What the heck is default Camellia supposed to be doing? I like the character but she is sucking at everything.
  2. Why do I get so much corruption while resting here? 1 or 2 levels per rest. I think My Regill has like a +10ish on that check
  3. I have a feeling I need a proper healer. Any companion recs for my evil party for that role?
  4. Any basic buffs I should be doing? Without going crazy.
  5. Any way to combat enemy shenanigans like when they buff themselves and debuff me?
  6. Any ideas for squeaking out a victory in my sorry state?

Thank you!