Ok, all of my questions revolve around his special damage power:

A Stinger That Could Break Rock: Poison deals penetrating damage. When he hits a character that can't use Toughness, Invulnerability, or Impervious, increase his damage dealt by 1.

Question 1: does using the literal power poison count as a hit?

Question 2: when using the literal power poison would this power effect it (ie. Make it penetrating poison)

Question 3: if poison's damage is at its max due to rule of 3, does he still modify the damage delt by +1

A1: No
A2: Yes
A3: No

Correct me if I'm wrong, but isn't damage dealt different from a modified damage value? This looks like a few similar powers where the damage is calculated after modifiers, much like a critical hit, meaning even if his damage is maxed due to the rule of 3, he would still do an additional damage.

Damage dealt is not a combat value. The rule of three does not apply to it.

Yes to question 3

A Stinger That Could Break Rock: Poison deals penetrating damage. When he hits a character that can't use Toughness, Invulnerability, or Impervious, increase his damage dealt by 1.

This specifically has the term "can't use". Does this activate if a power can't be used for any reason (trait, outwit) or only when something has been shut down using the "can't use" ability a la Nick Fury?

Thanks in advance.

It is looking at if the character can use the specified powers or not. If he hits a character that can use any of the specified powers he deals damage as normal. Otherwise he adds +1 to damage dealt.

It doesn't matter why the character cannot use any of the powers. Be it that it's countered, some game effect stating that it cannot be used or that the character simply doesn't have it.