does L/C protect you from "falling-off-elevated" damage?

it does not.
nothing in the power states that they do not take damage from falling of a building.

From the PAC:

From the FF starter booK, pg. 9:

So the answer is no.

Two things (technically 3) prevent getting knocked off elevated:

1. A character is in the square you'd get knocked onto. As such, you take a click of damage and remain on the elevated terrain.

2a. Charge. Characters with Charge can't be knocked back.

2b. An SP that says this character does not take knockback or the character does not take damage as a result of knockback.

There are other things aside from Charge, like being a transporter, double-based, or giant figure that do not get KBed.

Darn you and your details. Guess that's why you're an Orange...er, Fleshy(?) Lantern and I'm not.

Fleshy-headed mutant from sector 16B?

<snerk>

Those of us in Sector 7G have no idea what you're talking about.

Same goes for a character knocked back with phasing/teleport....they take 2 damage from the fall, right?

Phasing doesn't protect you.

How about a character with leapclimb who was successfully hit by knockback into a ledge of elevatede terrain?

Nothing in the power mentions anything about knockback. What makes you think they get any sort of special treatment if there's nothing in the rules to suggest that?

Understandable

You should have stopped after your first sentence, cause after that you totally sounded like a Grayson, if you get what I'm saying.

I was wondering this exact same question tonight and after reading some things I think there is a better way to explain it. Maybe it's been covered somewhere else but since this is where my queries led me I thought I would post my thought here.

Leap/Climb ignores the effects of elevated terrain on movement.

An "effect" is "A power, ability, or other rule than(typo? It should probably be "that"?) can affect a game.

I would definitely say knock back off of elevated terrain is an "effect" of elevated terrain, but the big thing that stops Leap/Climb from preventing knock back off of elevated terrain damage is the clarification that knock back is NOT A MOVEMENT.