Pre-Planning Sessions

I might be GMing a game of Dungeon World soon, so I thought I might post what I have planned to see if it is enough or too much or too little. I didn't make a full adventure or campaign front because I want to see how the first session plays out first. My players really like Ocean's 11 style bank-robbing capers, so I though I'd start out with something like that. I'll be posting about how the session goes if I can get a group together.
The Setup
The Vaults of the Bat-King contain the (probably empty) tomb of Hematophagous Rex, vampiric monarch, erstwhile demigod, and alleged dinosaur.
This however, is of secondary concern to my players, as the Vaults also contain the King’s Ransom, which consists of the incalculable sums of gold and magical items Hematophagous Rex’ worshippers used to bribe Death, so that their deity and king might be restored to life.
The Situation
There is a whole bunch of money at the bottom of the Vaults. The party is at the top. In between, the living worshippers of Bat-King, his undead minions, and rival grave-robbers stand in the way. The Vaults have three primary sections: the Chiropteran Cathedral, a functioning place of (militant) worship dedicated to the Bat-King; The City Subterranean, a necropolis filled with the animated remains of Hematophagous Rex’ hierophants and priests; and, finally, the Vaults Proper, guarded by the servants of Death and containing the incredibly valuable King’s Ransom
Danger: Humbleblood, Larcenous Sorcerer and Aspirant Demigod
“I would love to stay and chat, but I have relics to steal and people to smite. Divinity puts such a damper on one’s social life.”
Type: Arcane Enemy- Power-Mad Wizard
Impulse: to steal the King’s Ransom (and to use the wealth and artifacts therein to acquire followers)
Impending Doom: Tyranny
Humbleblood uses the King’s Ransom to acquire worshippers and a temple, thus completing the final step to godhead. (Also, the party loses out on a metric ton of gold.)
Grim Portents:
•   The party does not detect Humbleblood
•   Humbleblood acquires the key to the Ransom Chamber
•   Humbleblood escapes from the Vaults with the King’s Ransom
Filled in Spaces on the Map
The Chiropteran Cathedral
   Worshippers of the Bat-King are big on basalt and obsidian. Statues of men and bats and things in between line the walls of the Cathedral. The Cathedral is filled with worshippers and members of holy orders at all hours, though many retire to their ceiling-hammocks in the Atrium and Basement when the sun rises. The knights and priests of Hematophagous Rex will fight to the death, though worshippers can be reasoned with. The entry to the rest of the Vaults is in the Basement, but is obstructed by a magical seal.
The City Subterranean
   An entire underground city populated by the shambling remains of Hematophagous Rex’ deceased priests. The city itself is bowl shaped, consisting of a series of tiered circles. Most of the undead will react with hostility towards the party and are not  intelligent enough to be bargained with, but there are a (very) few who are willing and able to parley. At the bottom is a pit, which leads straight down into the Vaults Proper. Located somewhere in the City are:
Hundregore: a lich of considerable power. Willing to bargain with the party. Will teach a druid or anyone who can cast spells (including through multiclass stuff) to summon and control a certain spirit. I am still working on how the move will work, but I am thinking something a la the wizard’s Summon from World of Dungeons.
Mikhail Sergeyev: a vampire thrown into the City Subterranean by Chiropteran priests. He will pass on his…condition to an ambitious (or stupid) adventurer, provided they provide him with a way to escape the city. Rather nasty in a fight. Will flee if wounded.
The Vaults Proper
   The King’s Ransom is locked behind an adamant gate, which requires a key to open. The key is actually in the Vaults Proper—not due to design, but because an ancient grave-robber brought there before perishing. His body and they key are in one of the Vaults’ many twisting side passages. Hematophagous Rex quite literally paid for his unlife, and so Death guards his bribe jealously. In addition to various creatures from the Land of the Dead, there are two Concept Elementals. One is a Manifestation of Decay; the other is an Incarnation of Entropy. I am hoping my players surprise me with a way to bypass them, but I think I’ll say they can be negated through the presence of a spirit who governs an opposing sphere.

I haven’t quite figured out what the treasure will be.

In my opinion, you are way, way over prepped. The game really plays itself, you don't need a scenario that precise, especially for a first session.

Just make a front, exactly like it is in the book, and every so often, instead of describing the room to the players, ask questions about it. Seriously, on my second game of DW, my players made a riddle and couldn't figure out the answer, it was pretty great.

The whole game, from the GM's point of view, is about not sweating the small stuff. The evil wizard sounds awesome.

If you want an actual first session game, make a list of 6 likely monsters and start your session with the line "The vault's door closes behind you. There are evil forces at work in the Vaults of the Bat-King. What do you do?" And if they ask any questions about the environment, turn it on them, let them create your dungeon for you.

Thanks! Preparing this much is a hard habit to kick. Some of the worst sessions I had with Fourth Edition were under-prepped ones. But I definitely see what you mean. I think I based this too much off of the Temple of Ungu thing, which is more of a one-shot, rather than the Front section. I guess what's throwing me off is that I have always been a reactive GM. Like, the players enter a dungeon that is in some sort of stasis, and their actions set of a chain of events that have positive or negative consequences, whereas in DW it seems like a lot of things don't even exist until the players come into contact with them, and as that happens, things are happening in the background. Is that about right?

You don't even need a front to start the first session—read about it in the chapter "the first session", you will see preparation it's more a matter of being open minded and receptive than having stuff ready!

Adam speaks truth.

The hard part is to just accept that your players, as 3-5 creative minds, are probably able to make a more interesting story than you could on your own. It's about trust.

See yourself more like the audience of a Reality TV show. You are enjoying the hell out of that show and every now and then, the announcer asks the audience to call in and vote on what happens next! So just let them roll until everything stops and they look at you. Then pick a move and let them deal with it, see what happens. Rince and repeat.

"Don't use the Fronts rules (in the next chapter) for the first session either."
Wow. I read that chapter twice and totally missed that line.

I notice a lot of mention of leading questions. Should that be stuff like "You stand before the steel door of the Vault. What lies behind it?" or "You hear skittering in the darkness. What creature of the vaults do you fear the most?"

And thanks for the responses, guys. It feels like I should know this stuff, but you are being really helpful. I think I'll go back and RTFM again.

Here's something that has really helped our games lately, on the GM side of the table with regard to prep and execution:

The GM's job is to come up with problems, not solutions. Coming up with solutions is the players' job.

This helps with playing to find out what happens.

Have a look at the links below, that's my take on prep.  I think there's enough there that you could probably get a couple plays out of each one and have them all be different.

The Goblin Hole

Black Oak Ridge

The Shallow Sea

Should that be stuff like "You stand before the steel door of the Vault. What lies behind it?" or "You hear skittering in the darkness. What creature of the vaults do you fear the most?"

those are awesome questions, but I think it varies with the group, there is no question that's 100% useful for every group.

However, I would be more subtle. The "Getting Started" paragraph and the "Ask Questions" goal should clarify what I mean.

Examples of questions I asked the recent first session:
• how works your magic?
• how's organized your tribe?
• why would the evil cult attack you like this?
• how about your thieves guild?

When asking question, you should look for what's interesting for the players and their characters. You are gathering details, facts, motivations, that set in motion the story and basically build themselves the fronts for the future sessions. They describe their dear homeland? Someone attacks it. They describe an enemy? You have him raise to power. They declare important facts about setting-specific details—like the wizard who learned magic studying on powerful magic tome wich allows the owner to control spirits, found in a mystical cave with walls covered by arcane signs? Then someone tries to steal her that tome, while the cave becomes conscious and starts to spawn evil elementals all around.

The book is actually very clear about all those things. Check this quote:

The first adventure is really about finding out what future sessions will deal with.

And I'm speaking like a pro while I learned how to write fronts yesterday.

Rubi,

Questions (even leading questions) are your best friend.

Don't be hard on yourself.  DW is dressed like the games with Dragons in the name we all know and have played forever.  Learning to throw 2d6 is far less of a challenge than learning how to do the back-and-forth discussion, break your players of checking their sheets to use a move to start fiction, and teaching yourself to let go of the preconceptions of what an adventure is and how to structure it.

Start the game in-media rez.  Have someone cut through something, then ask what they're cutting through.  Ask someone else what they're most worried about here.  Ask the cleric what ancient relic of their religion is hidden here.  Ask the thief what treasure they heard was here, and offer them an XP if they find it.

Then look up the monsters, write down the stats for the item the first time you take a bathroom break, and hold on for the wild ride :)