RRG, Abilities, p2 wrote:
• If an ability is “used,” it can be triggered multiple times each
round, but it can only be triggered once per timing instance.
For example, an ability that says, “Use while attacking to apply
+1 damage to the attack results,” can only be triggered once during
That should answer the first question.
2nd question is about Parting Shot.
You can target anything you can normally target with an attack.