This is in regards to Light of Valinor and new Gandalf's ability.

Character "does not exhaust to commit to quests."

I'm wondering if this also allows us to use the character for something BEFORE the commit characters step (so they're exhausted already) and then we can still commit them to the quest…?

What are our thoughts on this?

No.

He must be ready in the first place.

Specifically, p.14 of the core rules discusses ready and exhausted states. Exhausted characters "cannot partake in any action that requires exhaustion." The general action of committing characters requires exhaustion, even if card text allows a specific character to commit without exhausting.

The same principle holds for attacking and defending.

I specifically asked FFG about this:

Rule Question:
If a hero has "Light of Valinor" attached (states "Attached hero does not exhaust to commit to a quest."), then can they commit to a quest when they are already exhausted?

Example: Glorfindal has both "Caught in a Web" and "Light of Valinor" attached to him. After exhausting in one round (for whatever reason) he does not refresh at the end of that round since he cannot pay the two resources for "Caught in a web". During the next round, will he be able to commit to a quest even though he is exhausted (provided "Light of Valinor" is still attached)?

Reply:

That's one of those questions that made me say "hmm" because I can follow your train of thought. However, the answer is no; a character cannot commit to a quest when exhausted.
Cheers,
Caleb