I’ve quite frequently run Warhammer stuff in BW.
Yes, BW thrives on character motivation and intent. In game parlance, their BITs* propel them and the story. As a GM, you want to make sure that what they want intersects with the adventures you’re looking to run.
Beliefs - what drives them, the goals they want to achieve (“I will drive the bandits from Sherwood Forest”)
Instincts - what they instinctively do, what habits they have (Always hide a knife)
Traits - prominent aspects of the character (Stubborn, Faith, One-Eyed)
Quite often, it’s either a case of holding onto the core of the adventure lightly or setting up a very strong situation and getting player buy-in to the core conceit of the adventure / campaign.
So, for “Shadows over Bögenhafen”, for instance, you want the characters heavily invested in the events and mysterious happenings, potentially some of them having strong ties to the merchant houses, or their enemies, etc.
In your pitch to the players, you’d ask for them to create characters strongly tied to the town, asking that one (or more) of them write a Belief that puts them at loggerheads with one of the merchant houses. You’d ensure that one of their Relationships cares deeply about (say) the drunken dwarf, you might suggest that one of them have a Relationship with the magistrate, etc.
Given how terrifying (for characters) the Fight! subsystem is, then you’d look to resolve a number of the “filling the time” fights from published scenarios either with a quick dice-roll or by stripping them out.
On the other hand, that big finale fight against that Chaos Sorcerer for the life of their mentor? That’s an awesome thing to get into!
Hrm. Re-reading, I’ve probably jumped a few too many steps ahead, given that you’re looking to potentially buy Burning Wheel.
Can I suggest having a look at the (free PDF) of the Hub and Spokes?
This is the core “loop” of the game, and does a great job of laying it out.
The game (wisely) recommends using pretty much just the Hub and Spokes until you want to dig deeper.