Don't know what video you're talking about or who you're referring to. I've only looked at the set's announcement article on their website, the card gallery, and a couple of Trump's videos.
The Quests do show what they give you in the gallery. It's only the Galakrond upgrades and the "upgraded Mage spell" from the new Malygos that are missing.
But okay, if they all quadruple and get that weapon fully upgraded, that is pretty potent. The Priest one becomes a board wipe against most boards plus a weapon, the Warlock one builds a probably-strong board plus gets the weapon, and the Rogue one is a sprint worth of 0-mana cards plus the weapon. All very strong, and if they upgrade in your deck, seems good to me.
If you're a deck that isn't token-based and can't remove them, sure. Most Control decks can probably do the latter, though, and more aggressive decks are more tokeny and less good for Dragonbane, however.
"Recycle Rogue?" What are you talking about?
I did not agree with your point, I was pointing out that the things you're comparing them for some kind of power level baseline have not been what we need to compare cards to for that for a very long time now, and in the case of the 6 drops never were.
Huh. Seems... odd and iffy to me. Not even sure Holy Wrath Paladin wants it, honestly, seems like it would just dilute the deck, being neither draw, removal, nor part of their combo. To them it would be just what, a way to use Shirvalla before the combo while still putting him back in your deck? I get why they might want that, but this would only work on turn 9+, and after he's already been reduced to cost 0 (or 1 at most), so you're already in the very late game by then. I don't know, it's certainly a big value card, but feels too conditional to me.
As Stevesciguy pointed out, it triggers the hero power, not the battlecry. So far, those are:
Rogue: Add a lackey to your hand.
Warlock: Summon two 1/1 Imps.
Priest: Add a random Priest minion to your hand.