Yeah, having a faceup card in your player deck would be analogous to peeking at the encounter deck with scry effects, which does not trigger when revealed effects.

I have to agree in this one with cmabr002 and GrandSpleen.

Having Gandalf hero in play and, as a consequence, the top card of deck turn faced up, isn't the same as revealing the top card of your deck.

Same applies to effects like Denethor and Henamarth Riversong that don't reveal the card from encounter deck.

So i would say, in my opinion, that Gandalf Hero + Vilya is possible

There is a difference between functionally revealed and game-mechanically revealed. When you look at the top card of the encounter deck, it is functionally revealed to you, but it doesn't trigger any game-mechanics of a card being revealed. The same difference is being applied to Gandalf's ability. While it is functionally revealed to everyone, it isn't "revealed" in a game-mechanic sense.

As for the Flame event, it has the format "Do X to do Y, Z also happens". If Y isn't possible, you cannot trigger the effect. Sam is different since his is "If X happens, do Y. Also do Z."

If it had been "If X happens, do Y then do Z" because of the use of "then", Y would need to resolve successfully before you could finish the sentence and do Z.