Best practice for building an e-commerce system with React Native, Django Admin, and FastAPI

I'm building an e-commerce platform using:

• React Native for the mobile frontend
• Django Admin for back-office product and order management
• FastAPI for providing async API services to the mobile app

I have a few questions:

1. Which framework should handle the CRUD logic for products, orders, etc. — Django or FastAPI?
2. Is it a good idea to let Django Admin call FastAPI for data, or should it access the database directly?
3. How should I structure the authentication system (e.g., JWT login)? Should FastAPI be the auth provider?
4. If I plan to add AI-based features, how should I structure that service alongside Django and FastAPI?
5. What's the recommended way to store and serve ML models (local folder, volume, or object storage)?

Any architectural suggestions or real-world examples are welcome. I'm using a shared MySQL database for both Django and FastAPI.

Thanks in advance!