For the question on how many classes can play 2 quests in a game assuming both players are running the quest in their deck:

Priest: via glimmerroot into quest

Rogue: hallucination into glimmerroot into quest

Druid/Shaman: Lotus assassins into hallucination into glimmerroot into quest

Warlock: renounce darkness into glimmerroot into quest (or just Kabal courier into glimmerroot)

Mage: Kabal courier into renounce which turns kazakus into glimmerroot into quest (or just Kabal courier into glimmerroot)

Warrior: explore un'goro into Elise trailblazer into pack into glimmerroot into quest

Paladin /Hunter: Grimestreet informant into explore un'goro into Elise trailblazer into pack into glimmerroot into quest

That's all nine classes assuming we control all rng