Regeneration, Crits, Coup de Grace Question

[myancey]

I saw the thread "Wait... Regeneration?!" and developed a question based on a character I have.

My character:
He is a Troll-blooded Changeling Fighter/Warshaper.

Main points to this character: Regeneration 1 and Crit Immunity.

Questions:

1) My character is immune to critical hits--does this benefit negate a coup de grace's automatic critical hit?

2) Based on a yes for question 1, wouldn't that mean normal damage--which translates into nonlethal for a regenerative character?

[Flickerdart]

"You can’t deliver a coup de grace against a creature that is immune to critical hits."

[Halae]

ake warshaper up to level 4 and you start healing the actually lethal damage too (the fire and acid damage). Take the feat Rapid regeneration from the fiendish Codex 2 and amp your regen score to be even more crazily awesome.

[Fouredged Sword]

Or get fire, acid, and non lethal damage immunity and laugh at damage.

[Reluctance]

Criticals just multiply the damage, and have no impact on the damage's type in any sense of the word.

You'd be immune to the autocrit effect of a critical. Fire damage is still fire damage is still lethal damage, and they still autohit you if you're unconscious. It'll take them longer, but you'll be just as dead in the end.

Also, I might be misremembering, but do changelings go back to their natural form when knocked unconscious? Warshaper bonuses only apply when you're in a form other than your natural one.