So yes, if any of the operations in the transaction fails (and cannot be retried) the whole transaction will fail. It's atomic as you'd expect. If you've ever used transactions in Firebase Realtime Database you'll be happy to know that the transactions in Cloud Firestore are much easier to use since they don't require selecting a common data parent.
Queries are always strongly consistent. If you do a write-read sequence you'll see the value of the latest write.
So yes, if any of the operations in the transaction fails (and cannot be retried) the whole transaction will fail. It's atomic as you'd expect. If you've ever used transactions in Firebase Realtime Database you'll be happy to know that the transactions in Cloud Firestore are much easier to use since they don't require selecting a common data parent.
Queries are always strongly consistent. If you do a write-read sequence you'll see the value of the latest write.