> I'm curious how this approach manages cardinality explosion?

The Knowledge Graph explicitly models cardinality and relationships between entities. The compiler uses that to generate SQL that handles it correctly, using e.g. DISTINCT

> Also, how do you handle cases where a user asks for data that requires running multiple queries, specifically where each query depends on the results of the previous one?

Veezoo can generate adaptive plans, so it can decide to wait for a database query to return results before continuing