The key deliverables in e-commerce development & deployment projects typically include:

1. Project Planning:
   • Developing a detailed project plan outlining the scope, timeline, and milestones of the e-commerce development.
2. Requirements Specification:
   • Clear documentation of functional and non-functional requirements based on stakeholder needs.
3. User Interface (UI) Design:
   • Design mockups and prototypes for the user interface, ensuring a user-friendly and visually appealing online store.
4. User Experience (UX) Design:
   • Focus on creating a seamless and enjoyable experience for users while navigating through the website or application.
5. Front-end Development:
   • Implementation of the user interface design, including the development of responsive web pages or mobile app screens.
6. Back-end Development:
   • Development of the server-side logic, databases, and application functionality that power the e-commerce platform.
7. Database Design:
   • Design and implementation of a robust database structure to store product information, user data, and transaction details securely.
8. Shopping Cart and Checkout System:
   • Implementation of a smooth and secure shopping cart system, as well as a reliable checkout process.
9. Payment Gateway Integration:
   • Integration of payment gateways to facilitate secure online transactions, supporting various payment methods.
10. Product Management:
    • Implementation of tools for managing product listings, including adding, updating, and removing products.
11. User Account Management:
    • Development of user registration, login, and profile management features.
12. Security Features:
    • Implementation of security measures to protect user data, secure transactions, and prevent common e-commerce security threats.
13. Order Management:
    • Creation of systems for you to manage and track customer orders, including order processing, fulfillment, and shipping.
14. Search Functionality:
    • Integration of an efficient search system to help users find products easily.
15. Analytics and Reporting:
    • Implementation of tools to track and analyze user behavior, sales data, and other relevant metrics.
16. Mobile Responsiveness:
    • Ensuring that the e-commerce platform is optimized for various devices, including smartphones and tablets.
17. Testing:
    • Rigorous testing of the entire e-commerce system to identify and fix bugs, ensure functionality, and enhance overall performance.
18. Documentation:
    • Comprehensive documentation that includes user manuals, system architecture, and code documentation for future reference and maintenance.
19. Training:
    • Training materials and sessions for administrators and users to effectively use and manage the e-commerce platform.
20. Deployment:
    • Successful deployment of the e-commerce platform to a production environment, making it accessible to users.
21. Maintenance and Support Plan:
    • A plan for ongoing maintenance, support, and updates to ensure the continued smooth operation of the e-commerce platform.
22. Compliance and Legal Considerations:
    • Ensure that the e-commerce platform complies with relevant laws and regulations, such as data protection and consumer rights.

Coming to an agreement on the abovementioned deliverables based on realistic timelines with adequate resources is in our opinion the best practice approach that contributes to the highest probability of successful development and deployment of robust e-commerce platforms.