My problem: when I'm fighting and retreating, my player's back is to the enemy. Instead of turning, I'd like him to take a step backwards.

I've noticed that with a crossbow in hand, the player no longer turns when you back up, but instead follows the rotation of the camera.

Suggestion: Add an entry in the config to add a “combat” mode when a weapon is in hand (sword, bow...) as when he's holding a crossbow.

You could either enable this permanently by setting decoupled_camera to false or add all weapons to the adaptive crosshair items (hold) lists: adaptive_crosshair_hold_items.