How can I limit the number of items being deleted (I'm using the adapter scenario) without fetching the records first? So basically, I want to construct a query like "DELETE TOP 100 FROM ....". Is this possible?

There is no direct way to implement this, but you can use the RelationPredicateBucket parameter to pass a FieldCompareSetPredicate to filter on the same table using TOP, something that should produce the following:

DELETE FROM Customer
WHERE Id IN (SELECT TOP 100 Id FROM Customer WHERE .....)

Thanks, that worked.