So you are playing a metric ton of mediocre/bad cards (like Wisps) to get some value out of this Quest and then play a horrible card on that turn just to get gains from it later?
That has never worked out well in the history of Hearthstone. Usually you can afford to play a few mediocre/bad cards if the synergy is insane (like playing a bunch of mediocre Hunter Secrets to get the nuts play Cloaked Huntress) but this is the type of deck where you need quite a bit of these weird cards to make the quest work consistently.
And again, what are you actually beating with this kind of deck? You can beat control decks but Rogue already excels at beating control decks. Can you beat Midrange/curve decks with this? By the time you get to activate the quest, a Jade deck is going to be pumping out 5/5s too.
Since the quest focuses on minions that means that you need a healthy amount of minions in your deck which means stuff like Shadowstep loses some value after the quest has been played. And Rogue usually has a good number of spells in their deck.
You're making way too many assumptions here, along with some rather hasty dismissals. Wisp is just one example of a card that could make it easy to activate or benefit from the quest. I actually think the wisp idea is elegant because if you manage to activate it on turn 5 with wisp, you can play the quest immediately or with prep. Wisp is a "bad" card in the context of a deck that cannot fully utilize a 0 mana minion. Just like paladin secrets were before mysterious challenger. Hell, even gadgetzan ferryman is potentially good here because after the portal is activated, maybe bouncing a minion is not necessary or perhaps even detrimental. Jury is still out on that, but it's a consideration.
Back to novice engineer, this I think will be a very strong card to use. Play novice and shadowstep. Next turn maybe novice and bounce back to hand with brewmaster. Cycling your deck while completing the quest should be strong, along with the van cleef synergy I mentioned earlier which is a time tested way to activate van cleef.
And your questions are basically asking for answers to metagame calls that no one can predict at this point. No deck lists exist at this point. Several staple miracle rogue cards are being cycled and many new cards and mechanics are being introduced.
I think this rogue quest can be built to be activated faster than any other quest we've seen so far. The minimum amount of cards required to activate it is just 5. The shaman one is close, if not faster assuming call in the finishers.
Also people bringing up jade again. It's hard to say how fast the deck will be at activating the quest on average. I'd say fairly fast tbh. Jade usually doesn't ramp up that fast and this deck is going to move much faster than jade will. Jade is typically not a problem for rogue, and I think this deck will have even more interesting tool possibilities. One would be vanish which can set back a jade deck to an empty board while rogue replays their cheap minions filling the board with 5/5s on their side. Even devolve won't do much as they presumably remain 5/5s after devolve.