One note to add: in SQLite, during a transaction, all other write access is simply forbidden. That matters a lot if your list of queries can take many seconds to complete... No, they're not queued, SQLite just will make you wait until the transaction ends, up to as long as the timeout you allowed, and then, if you still got no access, cause a fatal error.

Basically, if you can have transactions that take several seconds, any other writing access to the database is impractical. Unless you're prepared to wait for a long time...