1. I'd say we are still in "beta". We are quickly adding new features and updating our APIs. I don't have specific users I know that are using the Python library in production, but I'm sure they are out there.
2. Yes, this can write data to a delta table, and commit them in transactions. (Not sure what you mean by "without transactions")
3. The main caveat is we don't support newer protocol versions yet. So table features like column mapping and constraints aren't yet supported.